typo "deay" -> "decay"
Author: KazutoshiShinoda
Pull request: yes

a typo has been fixed.

Comments:
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/1853?src=pr&el=h1) Report
> Merging [#1853](https://codecov.io/gh/huggingface/transformers/pull/1853?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/0477b307c7501ea76e01b03cb387a2312db752b3?src=pr&el=desc) will **decrease** coverage by `0.09%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/1853/graphs/tree.svg?width=650&token=9qOlN6Hb1c&height=150&src=pr)](https://codecov.io/gh/huggingface/transformers/pull/1853?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##           master    #1853     +/-   ##
=========================================
- Coverage   84.08%   83.98%   -0.1%     
=========================================
  Files          97       97             
  Lines       14316    14316             
=========================================
- Hits        12037    12023     -14     
- Misses       2279     2293     +14
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/1853?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [transformers/tests/modeling\_tf\_auto\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX2F1dG9fdGVzdC5weQ==) | `96.36% <0%> (-1.82%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_transfo\_xl\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX3RyYW5zZm9feGxfdGVzdC5weQ==) | `93% <0%> (-1%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_ctrl\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX2N0cmxfdGVzdC5weQ==) | `93.06% <0%> (-1%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_distilbert\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX2Rpc3RpbGJlcnRfdGVzdC5weQ==) | `98.16% <0%> (-0.92%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_openai\_gpt\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX29wZW5haV9ncHRfdGVzdC5weQ==) | `93.85% <0%> (-0.88%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_gpt2\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX2dwdDJfdGVzdC5weQ==) | `93.85% <0%> (-0.88%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_xlm\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX3hsbV90ZXN0LnB5) | `94.35% <0%> (-0.81%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_roberta\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX3JvYmVydGFfdGVzdC5weQ==) | `74.4% <0%> (-0.8%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_xlnet\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX3hsbmV0X3Rlc3QucHk=) | `95.03% <0%> (-0.71%)` | :arrow_down: |
| [transformers/tests/modeling\_tf\_bert\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX2JlcnRfdGVzdC5weQ==) | `95.59% <0%> (-0.63%)` | :arrow_down: |
| ... and [2 more](https://codecov.io/gh/huggingface/transformers/pull/1853/diff?src=pr&el=tree-more) | |

------

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> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/1853?src=pr&el=footer). Last update [0477b30...de3cb08](https://codecov.io/gh/huggingface/transformers/pull/1853?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).