Clean-up code
Looks like #4747 introduced some bad formatting, fixing so CI is happy again.
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=h1) Report
> Merging [#4790](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/fa661ce749b0d14ae1999d1b097866248624a842&el=desc) will **increase** coverage by `0.01%`.
> The diff coverage is `100.00%`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/4790/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #4790      +/-   ##
==========================================
+ Coverage   76.28%   76.29%   +0.01%     
==========================================
  Files         128      128              
  Lines       21500    21500              
==========================================
+ Hits        16401    16404       +3     
+ Misses       5099     5096       -3     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/configuration\_xlnet.py](https://codecov.io/gh/huggingface/transformers/pull/4790/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9jb25maWd1cmF0aW9uX3hsbmV0LnB5) | `94.00% <100.00%> (ø)` | |
| [src/transformers/modeling\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/4790/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl91dGlscy5weQ==) | `87.51% <0.00%> (+0.31%)` | :arrow_up: |
| [src/transformers/file\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/4790/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9maWxlX3V0aWxzLnB5) | `74.27% <0.00%> (+0.41%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=footer). Last update [fa661ce...a3f8a97](https://codecov.io/gh/huggingface/transformers/pull/4790?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
<|||||>👍 