Refine parameter type annotations
Author: flashJd
Pull request: yes

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Fixes # (issue)
This PR refines the parameter type annotations in the add_tokens and add_special_tokens methods.`special_tokens_dict` parameter accept list or tuple when key is additional_special_tokens, but parameter type not covered.
The goal is to make the parameter type more clear

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Comments:
Hi 👋, thank you for opening this pull request! The pull request is converted to draft by default. When it is ready for review, please click the `Ready for review` button (at the bottom of the PR page).

I checked the tests failure:
`test_eager_matches_sdpa_inference_1_bfloat16` failure has nothing to do with my code changes
`test_add_special_tokens` failed because of https ReadTimeout, I run the test local and passed.

`python -m unittest tests.models.nougat.test_tokenization_nougat.NougatTokenizationTest.test_add_special_tokens
Ran 1 test in 3.781s
OK`

Yes, these test failures are unrelated - we're fixing the CI issue internally, so hopefully we can rebase and merge this PR afterwards!

Hi @flashJd, I think everything should be solved by rebasing onto the latest version of `main` and force pushing but the Github interface is acting strangely. Can you do the rebase/force push manually and ping me to merge this?

I've rebased the main branch, @Rocketknight1

@flashJd sorry for the delay, but the CI still looks red! I'm not sure why - can you try rebasing again or retriggering tests until it passes? There may just be something flaky in the CI.

@Rocketknight1 , It maybe github issue, so I closed this pr and opened a new one, https://github.com/huggingface/transformers/pull/37666