TypeError: __init__() got an unexpected keyword argument 'save_strategy'
### Environment
- `transformers` version: 4.2.2
- Platform: Linux-4.15.0-151-generic-x86_64-with-glibc2.10
- Python version: 3.8.5
- PyTorch version (GPU?): 1.4.0 (True)
- Tensorflow version (GPU?): not installed (NA)
- Using GPU in script?: Not explicitly (but probably)
- Using distributed or parallel set-up in script?: Not explicitly (but probably)

### Who can help
@sgugger

### Details
I am using RoBERTa for seq classification, but that is not where my issue is coming from. My issue is coming from the Trainer API. Specifically, when I try to specify save_strategy=epoch in TrainingArguments, I get the error message in the issue title. I tried updating to a more recent version of Transformers as per another issue, but that didn't work. I'm not sure what to do about it.
You probably did not properly install it. The environment above shows 4.2.2 and `save_strategy` was introduced later on.
You can check the version of Transformers executed by your script by adding
```
import transformers
print(transformers.__version__)
```
at the top of it.<|||||>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.