Add decorator as explicit test dependency

Add decorator as explicit test dependency.

We use `decorator` library in our CI test since PR:
- #4845

However we did not add it as an explicit test requirement, and we depended on it indirectly through other libraries' dependencies.

I discovered this while testing Numpy 2.0 and removing incompatible libraries.

Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7043). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

<details>
<summary>Show benchmarks</summary>

PyArrow==8.0.0

<details>
<summary>Show updated benchmarks!</summary>

### Benchmark: benchmark_array_xd.json

| metric | read_batch_formatted_as_numpy after write_array2d | read_batch_formatted_as_numpy after write_flattened_sequence | read_batch_formatted_as_numpy after write_nested_sequence | read_batch_unformated after write_array2d | read_batch_unformated after write_flattened_sequence | read_batch_unformated after write_nested_sequence | read_col_formatted_as_numpy after write_array2d | read_col_formatted_as_numpy after write_flattened_sequence | read_col_formatted_as_numpy after write_nested_sequence | read_col_unformated after write_array2d | read_col_unformated after write_flattened_sequence | read_col_unformated after write_nested_sequence | read_formatted_as_numpy after write_array2d | read_formatted_as_numpy after write_flattened_sequence | read_formatted_as_numpy after write_nested_sequence | read_unformated after write_array2d | read_unformated after write_flattened_sequence | read_unformated after write_nested_sequence | write_array2d | write_flattened_sequence | write_nested_sequence |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.005147 / 0.011353 (-0.006205) | 0.003403 / 0.011008 (-0.007605) | 0.061367 / 0.038508 (0.022859) | 0.030295 / 0.023109 (0.007186) | 0.233503 / 0.275898 (-0.042395) | 0.252644 / 0.323480 (-0.070836) | 0.004072 / 0.007986 (-0.003913) | 0.002678 / 0.004328 (-0.001650) | 0.049099 / 0.004250 (0.044848) | 0.043032 / 0.037052 (0.005979) | 0.248823 / 0.258489 (-0.009666) | 0.274895 / 0.293841 (-0.018946) | 0.029307 / 0.128546 (-0.099239) | 0.011186 / 0.075646 (-0.064460) | 0.197142 / 0.419271 (-0.222129) | 0.035924 / 0.043533 (-0.007609) | 0.234728 / 0.255139 (-0.020411) | 0.252990 / 0.283200 (-0.030209) | 0.017589 / 0.141683 (-0.124094) | 1.108252 / 1.452155 (-0.343903) | 1.135949 / 1.492716 (-0.356767) |

### Benchmark: benchmark_getitem\_100B.json

| metric | get_batch_of\_1024\_random_rows | get_batch_of\_1024\_rows | get_first_row | get_last_row |
|--------|---|---|---|---|
| new / old (diff) | 0.093096 / 0.018006 (0.075090) | 0.289284 / 0.000490 (0.288794) | 0.000208 / 0.000200 (0.000008) | 0.000038 / 0.000054 (-0.000016) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.017633 / 0.037411 (-0.019778) | 0.060621 / 0.014526 (0.046095) | 0.073194 / 0.176557 (-0.103363) | 0.120176 / 0.737135 (-0.616959) | 0.073575 / 0.296338 (-0.222764) |

### Benchmark: benchmark_iterating.json

| metric | read 5000 | read 50000 | read_batch 50000 10 | read_batch 50000 100 | read_batch 50000 1000 | read_formatted numpy 5000 | read_formatted pandas 5000 | read_formatted tensorflow 5000 | read_formatted torch 5000 | read_formatted_batch numpy 5000 10 | read_formatted_batch numpy 5000 1000 | shuffled read 5000 | shuffled read 50000 | shuffled read_batch 50000 10 | shuffled read_batch 50000 100 | shuffled read_batch 50000 1000 | shuffled read_formatted numpy 5000 | shuffled read_formatted_batch numpy 5000 10 | shuffled read_formatted_batch numpy 5000 1000 |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.277168 / 0.215209 (0.061959) | 2.689714 / 2.077655 (0.612060) | 1.427558 / 1.504120 (-0.076562) | 1.331350 / 1.541195 (-0.209844) | 1.353069 / 1.468490 (-0.115421) | 0.716657 / 4.584777 (-3.868120) | 2.321145 / 3.745712 (-1.424567) | 2.757986 / 5.269862 (-2.511876) | 1.851604 / 4.565676 (-2.714072) | 0.089530 / 0.424275 (-0.334745) | 0.004884 / 0.007607 (-0.002723) | 0.327859 / 0.226044 (0.101814) | 3.290749 / 2.268929 (1.021821) | 1.831090 / 55.444624 (-53.613535) | 1.509247 / 6.876477 (-5.367229) | 1.616545 / 2.142072 (-0.525527) | 0.775228 / 4.805227 (-4.029999) | 0.133794 / 6.500664 (-6.366870) | 0.040644 / 0.075469 (-0.034825) |

### Benchmark: benchmark_map_filter.json

| metric | filter | map fast-tokenizer batched | map identity | map identity batched | map no-op batched | map no-op batched numpy | map no-op batched pandas | map no-op batched pytorch | map no-op batched tensorflow |
|--------|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.950816 / 1.841788 (-0.890972) | 11.109938 / 8.074308 (3.035630) | 9.560673 / 10.191392 (-0.630719) | 0.130685 / 0.680424 (-0.549738) | 0.014096 / 0.534201 (-0.520105) | 0.297222 / 0.579283 (-0.282061) | 0.262777 / 0.434364 (-0.171587) | 0.340983 / 0.540337 (-0.199355) | 0.426107 / 1.386936 (-0.960829) |

</details>
PyArrow==latest

<details>
<summary>Show updated benchmarks!</summary>

### Benchmark: benchmark_array_xd.json

| metric | read_batch_formatted_as_numpy after write_array2d | read_batch_formatted_as_numpy after write_flattened_sequence | read_batch_formatted_as_numpy after write_nested_sequence | read_batch_unformated after write_array2d | read_batch_unformated after write_flattened_sequence | read_batch_unformated after write_nested_sequence | read_col_formatted_as_numpy after write_array2d | read_col_formatted_as_numpy after write_flattened_sequence | read_col_formatted_as_numpy after write_nested_sequence | read_col_unformated after write_array2d | read_col_unformated after write_flattened_sequence | read_col_unformated after write_nested_sequence | read_formatted_as_numpy after write_array2d | read_formatted_as_numpy after write_flattened_sequence | read_formatted_as_numpy after write_nested_sequence | read_unformated after write_array2d | read_unformated after write_flattened_sequence | read_unformated after write_nested_sequence | write_array2d | write_flattened_sequence | write_nested_sequence |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.005547 / 0.011353 (-0.005806) | 0.003425 / 0.011008 (-0.007584) | 0.049791 / 0.038508 (0.011283) | 0.032660 / 0.023109 (0.009550) | 0.257640 / 0.275898 (-0.018258) | 0.283483 / 0.323480 (-0.039997) | 0.004330 / 0.007986 (-0.003655) | 0.002297 / 0.004328 (-0.002032) | 0.047999 / 0.004250 (0.043748) | 0.039875 / 0.037052 (0.002822) | 0.273300 / 0.258489 (0.014811) | 0.303384 / 0.293841 (0.009543) | 0.031696 / 0.128546 (-0.096851) | 0.011913 / 0.075646 (-0.063733) | 0.060330 / 0.419271 (-0.358942) | 0.033253 / 0.043533 (-0.010280) | 0.255378 / 0.255139 (0.000240) | 0.271647 / 0.283200 (-0.011553) | 0.018772 / 0.141683 (-0.122910) | 1.116079 / 1.452155 (-0.336075) | 1.165133 / 1.492716 (-0.327583) |

### Benchmark: benchmark_getitem\_100B.json

| metric | get_batch_of\_1024\_random_rows | get_batch_of\_1024\_rows | get_first_row | get_last_row |
|--------|---|---|---|---|
| new / old (diff) | 0.094325 / 0.018006 (0.076319) | 0.297523 / 0.000490 (0.297034) | 0.000210 / 0.000200 (0.000011) | 0.000047 / 0.000054 (-0.000007) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.022485 / 0.037411 (-0.014926) | 0.073731 / 0.014526 (0.059205) | 0.089039 / 0.176557 (-0.087518) | 0.124035 / 0.737135 (-0.613101) | 0.088053 / 0.296338 (-0.208286) |

### Benchmark: benchmark_iterating.json

| metric | read 5000 | read 50000 | read_batch 50000 10 | read_batch 50000 100 | read_batch 50000 1000 | read_formatted numpy 5000 | read_formatted pandas 5000 | read_formatted tensorflow 5000 | read_formatted torch 5000 | read_formatted_batch numpy 5000 10 | read_formatted_batch numpy 5000 1000 | shuffled read 5000 | shuffled read 50000 | shuffled read_batch 50000 10 | shuffled read_batch 50000 100 | shuffled read_batch 50000 1000 | shuffled read_formatted numpy 5000 | shuffled read_formatted_batch numpy 5000 10 | shuffled read_formatted_batch numpy 5000 1000 |
|--------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.286676 / 0.215209 (0.071467) | 2.794678 / 2.077655 (0.717024) | 1.541401 / 1.504120 (0.037281) | 1.432928 / 1.541195 (-0.108267) | 1.454940 / 1.468490 (-0.013550) | 0.721779 / 4.584777 (-3.862998) | 0.956514 / 3.745712 (-2.789198) | 2.889533 / 5.269862 (-2.380329) | 1.863980 / 4.565676 (-2.701696) | 0.078366 / 0.424275 (-0.345909) | 0.005137 / 0.007607 (-0.002470) | 0.338835 / 0.226044 (0.112791) | 3.320921 / 2.268929 (1.051993) | 1.903654 / 55.444624 (-53.540970) | 1.615294 / 6.876477 (-5.261182) | 1.624777 / 2.142072 (-0.517295) | 0.792417 / 4.805227 (-4.012810) | 0.133321 / 6.500664 (-6.367343) | 0.040127 / 0.075469 (-0.035342) |

### Benchmark: benchmark_map_filter.json

| metric | filter | map fast-tokenizer batched | map identity | map identity batched | map no-op batched | map no-op batched numpy | map no-op batched pandas | map no-op batched pytorch | map no-op batched tensorflow |
|--------|---|---|---|---|---|---|---|---|---|
| new / old (diff) | 0.982357 / 1.841788 (-0.859430) | 11.585106 / 8.074308 (3.510798) | 9.991577 / 10.191392 (-0.199815) | 0.149292 / 0.680424 (-0.531131) | 0.015693 / 0.534201 (-0.518508) | 0.297416 / 0.579283 (-0.281867) | 0.118565 / 0.434364 (-0.315799) | 0.335640 / 0.540337 (-0.204697) | 0.429484 / 1.386936 (-0.957452) |

</details>
</details>

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