Incorrect type for TrainerArgs#report_to
### System Info

A minor thing...
The type of the `TrainerArgs` `report_to` argument is defined here: https://github.com/huggingface/transformers/blob/main/src/transformers/training_args.py#L901 as `Optional[List[str]]`, but the [docstring](https://github.com/huggingface/transformers/blob/main/src/transformers/training_args.py#L430) describes `Optional[str | List[str]]`. The default is wrong too.

### Who can help?

_No response_

### Information

- [ ] The official example scripts
- [ ] My own modified scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

NA

### Expected behavior

NA
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/main/CONTRIBUTING.md) are likely to be ignored.<|||||>I would like to politely question the logic of auto-closing issues. Do you not want GitHub issues to be a register of things that should be fixed? Auto-closing just means this bug will live on to annoy another user at some point in the future, and maybe they'll report it too.