Temporarily pin pydantic test dependency

Temporarily pin `pydantic` until a permanent solution is found.

Fix #5394.


_The documentation is not available anymore as the PR was closed or merged._

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

PyArrow==6.0.0

<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) | 0.012220 / 0.011353 (0.000867) | 0.005943 / 0.011008 (-0.005065) | 0.128223 / 0.038508 (0.089715) | 0.037352 / 0.023109 (0.014242) | 0.397143 / 0.275898 (0.121245) | 0.483935 / 0.323480 (0.160455) | 0.010279 / 0.007986 (0.002293) | 0.004842 / 0.004328 (0.000513) | 0.101403 / 0.004250 (0.097153) | 0.042935 / 0.037052 (0.005883) | 0.421642 / 0.258489 (0.163153) | 0.456328 / 0.293841 (0.162487) | 0.065639 / 0.128546 (-0.062907) | 0.019820 / 0.075646 (-0.055826) | 0.426090 / 0.419271 (0.006818) | 0.069583 / 0.043533 (0.026051) | 0.402662 / 0.255139 (0.147523) | 0.428826 / 0.283200 (0.145626) | 0.116760 / 0.141683 (-0.024923) | 1.806216 / 1.452155 (0.354061) | 1.852629 / 1.492716 (0.359913) |

### 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) | 0.226555 / 0.018006 (0.208548) | 0.584693 / 0.000490 (0.584203) | 0.008612 / 0.000200 (0.008412) | 0.000205 / 0.000054 (0.000150) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.028393 / 0.037411 (-0.009018) | 0.123355 / 0.014526 (0.108829) | 0.134423 / 0.176557 (-0.042133) | 0.188536 / 0.737135 (-0.548600) | 0.141595 / 0.296338 (-0.154743) |

### 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) | 0.589359 / 0.215209 (0.374150) | 5.974655 / 2.077655 (3.897001) | 2.465580 / 1.504120 (0.961460) | 2.007618 / 1.541195 (0.466424) | 2.078788 / 1.468490 (0.610298) | 1.216646 / 4.584777 (-3.368131) | 5.217516 / 3.745712 (1.471804) | 3.107188 / 5.269862 (-2.162674) | 2.251641 / 4.565676 (-2.314036) | 0.138640 / 0.424275 (-0.285635) | 0.015046 / 0.007607 (0.007439) | 0.780092 / 0.226044 (0.554048) | 7.749564 / 2.268929 (5.480635) | 3.080708 / 55.444624 (-52.363917) | 2.393897 / 6.876477 (-4.482579) | 2.387738 / 2.142072 (0.245665) | 1.458844 / 4.805227 (-3.346384) | 0.252476 / 6.500664 (-6.248188) | 0.076594 / 0.075469 (0.001125) |

### 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) | 1.540868 / 1.841788 (-0.300919) | 17.295684 / 8.074308 (9.221376) | 19.669300 / 10.191392 (9.477908) | 0.250315 / 0.680424 (-0.430109) | 0.045068 / 0.534201 (-0.489133) | 0.538840 / 0.579283 (-0.040443) | 0.584443 / 0.434364 (0.150079) | 0.614476 / 0.540337 (0.074138) | 0.729928 / 1.386936 (-0.657008) |

</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) | 0.009218 / 0.011353 (-0.002135) | 0.006261 / 0.011008 (-0.004747) | 0.125541 / 0.038508 (0.087033) | 0.034405 / 0.023109 (0.011296) | 0.468381 / 0.275898 (0.192483) | 0.503336 / 0.323480 (0.179856) | 0.006839 / 0.007986 (-0.001146) | 0.004724 / 0.004328 (0.000396) | 0.097875 / 0.004250 (0.093625) | 0.051278 / 0.037052 (0.014225) | 0.473323 / 0.258489 (0.214834) | 0.537392 / 0.293841 (0.243551) | 0.055588 / 0.128546 (-0.072958) | 0.021041 / 0.075646 (-0.054605) | 0.416952 / 0.419271 (-0.002320) | 0.070128 / 0.043533 (0.026595) | 0.465224 / 0.255139 (0.210085) | 0.504678 / 0.283200 (0.221478) | 0.112504 / 0.141683 (-0.029179) | 1.865865 / 1.452155 (0.413710) | 1.988296 / 1.492716 (0.495580) |

### 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) | 0.314170 / 0.018006 (0.296164) | 0.526726 / 0.000490 (0.526236) | 0.018691 / 0.000200 (0.018491) | 0.000128 / 0.000054 (0.000073) |

### Benchmark: benchmark_indices_mapping.json

| metric | select | shard | shuffle | sort | train_test_split |
|--------|---|---|---|---|---|
| new / old (diff) | 0.033772 / 0.037411 (-0.003639) | 0.124796 / 0.014526 (0.110270) | 0.134700 / 0.176557 (-0.041856) | 0.190595 / 0.737135 (-0.546541) | 0.143205 / 0.296338 (-0.153133) |

### 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) | 0.656708 / 0.215209 (0.441499) | 6.470503 / 2.077655 (4.392848) | 2.866430 / 1.504120 (1.362310) | 2.506846 / 1.541195 (0.965651) | 2.548669 / 1.468490 (1.080179) | 1.226695 / 4.584777 (-3.358082) | 5.117866 / 3.745712 (1.372153) | 3.032822 / 5.269862 (-2.237040) | 1.999152 / 4.565676 (-2.566524) | 0.142974 / 0.424275 (-0.281301) | 0.015011 / 0.007607 (0.007404) | 0.799729 / 0.226044 (0.573684) | 8.286313 / 2.268929 (6.017385) | 3.636482 / 55.444624 (-51.808142) | 2.888038 / 6.876477 (-3.988439) | 2.924982 / 2.142072 (0.782910) | 1.471996 / 4.805227 (-3.333231) | 0.257119 / 6.500664 (-6.243545) | 0.077294 / 0.075469 (0.001825) |

### 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) | 1.608290 / 1.841788 (-0.233497) | 17.599119 / 8.074308 (9.524811) | 18.917086 / 10.191392 (8.725694) | 0.236237 / 0.680424 (-0.444187) | 0.026061 / 0.534201 (-0.508140) | 0.527359 / 0.579283 (-0.051925) | 0.589176 / 0.434364 (0.154812) | 0.602310 / 0.540337 (0.061973) | 0.726756 / 1.386936 (-0.660180) |

</details>
</details>

![](https://cml.dev/watermark.png "CML watermark")


Issue reported to `pydantic`: 
- https://github.com/pydantic/pydantic/issues/4885

Fixing PR at `pydantic`:
- https://github.com/pydantic/pydantic/pull/4886