TrOCR not working anymore after 4.16.2 update
## Environment info
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     Don't forget to fill out the missing fields in that output! -->

- `transformers` version: 4.16.2
- Platform:  Colab
- Python version: 3.8?
- PyTorch version (GPU?): latest in colab
- Tensorflow version (GPU?):
- Using GPU in script?: Yes
- Using distributed or parallel set-up in script?:

### Who can help
Models:
TrOCR @NielsRogge  

I believe something has happened to the Trainer class that now makes evaluation of NielsRogge's TrOCR  model run into a bug. 

I have reproduced his notebook here, and encountered the bug when using the latest transformers version. 
  https://colab.research.google.com/drive/1ZcwbH_JzBMT7M84eDkUw9eJRqBxyofkB?usp=sharing


Thanks for reporting, this has been fixed in #15603.

For now, you have to install from source to have it: 

`pip install git+https://github.com/huggingface/transformers`<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md) are likely to be ignored.