add Tuple as possible type hint for EvalPredictions label_ids
# What does this PR do?
This adds Tuple as a type hint for the label_ids attribute in EvalPredictions. It is a valid type that label_ids can have.

## Before submitting
- [X] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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- [ ] Did you write any new necessary tests?

@stas00

If that's the case, then for consistency the following 2 classes should have the proposed changed as well.

@sgugger, what do you think?