Fix typing in docstring for PaliGemmaProcessor

[alvarobartt]

What does this PR do?

This PR updates the typing for tokenizer in the PaliGemmaProcessor to be GemmaTokenizerFast instead of LlamaTokenizerFast.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline, Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the documentation guidelines, and here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

Not sure who to tag, maybe @molbap as he contributed to the model AFAIK, feel free to ping anyone else if needed (sorry if that's the case)

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[molbap]

Indeed, thanks for the documentation update!

[ArthurZucker]

Thanks!