Add Microsoft's CodeBERT
Author: JetRunner
Pull request: yes
Labels: name: model card

@guoday

Comments:
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=h1) Report
> Merging [#5683](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/7fad617dc1fc681a7f5da5e0172c8b83f4bf0024&el=desc) will **decrease** coverage by `0.75%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/5683/graphs/tree.svg?width=650&height=150&src=pr&token=9qOlN6Hb1c)](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #5683      +/-   ##
==========================================
- Coverage   78.11%   77.36%   -0.76%     
==========================================
  Files         146      146              
  Lines       25983    25983              
==========================================
- Hits        20297    20102     -195     
- Misses       5686     5881     +195     
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [src/transformers/modeling\_tf\_mobilebert.py](https://codecov.io/gh/huggingface/transformers/pull/5683/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9tb2JpbGViZXJ0LnB5) | `23.38% <0.00%> (-73.39%)` | :arrow_down: |
| [src/transformers/modeling\_tf\_gpt2.py](https://codecov.io/gh/huggingface/transformers/pull/5683/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9ncHQyLnB5) | `63.55% <0.00%> (-31.78%)` | :arrow_down: |
| [src/transformers/generation\_tf\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/5683/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9nZW5lcmF0aW9uX3RmX3V0aWxzLnB5) | `85.71% <0.00%> (-0.26%)` | :arrow_down: |
| [src/transformers/modeling\_openai.py](https://codecov.io/gh/huggingface/transformers/pull/5683/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ19vcGVuYWkucHk=) | `82.31% <0.00%> (+1.28%)` | :arrow_up: |
| [src/transformers/modeling\_tf\_roberta.py](https://codecov.io/gh/huggingface/transformers/pull/5683/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9yb2JlcnRhLnB5) | `93.36% <0.00%> (+49.37%)` | :arrow_up: |
| [src/transformers/modeling\_tf\_openai.py](https://codecov.io/gh/huggingface/transformers/pull/5683/diff?src=pr&el=tree#diff-c3JjL3RyYW5zZm9ybWVycy9tb2RlbGluZ190Zl9vcGVuYWkucHk=) | `95.18% <0.00%> (+74.91%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=continue).
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> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=footer). Last update [7fad617...cbd3d7a](https://codecov.io/gh/huggingface/transformers/pull/5683?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).


> @guoday

Hi, @JetRunner .
Thanks a lot. It look great.