[Whisper] Fix word-level timestamps for audio < 30 seconds (#25607)
* Fix word-level timestamps for audio < 30 seconds
* Fix code quality
* fix unit tests
* Fix unit tests
* Fix unit test
* temp: print out result
* temp: set max diff to None
* fix unit tests
* fix typo
* Fix typo
Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>
* Use generation config for `num_frames`
* fix docs
* Move `num_frames` to kwargs
* compute stride/attn_mask once
* mark test as slow
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Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>
Co-authored-by: sanchit-gandhi <sanchit@huggingface.co>