fix Whisper tests on GPU
# What does this PR do?

The daily CI showed that Whisper has new test failures, related to the recent merge of the prompting feature. This PR fixes those test failures.

The tests ran OK on CPU but failed on GPU because the input data wasn't moved to the GPU.

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [x] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [x] Did you write any new necessary tests?


## Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

_The documentation is not available anymore as the PR was closed or merged._<|||||>Also skipping a few tests in `WhisperModelTest` that were previously skipped in `WhisperEncoderModelTest`, see https://github.com/huggingface/transformers/pull/22060

Although I just saw there's another open PR dealing with the same issue, so maybe none of these should be skipped: https://github.com/huggingface/transformers/pull/22803<|||||>Thanks again!