Fix PermissionError while creating '.no_exist/' directory in cache

[Wauplin]

Should fix huggingface/transformers#33897 (cc @sanketsudake).

When trying to download a file that doesn't exist on a remote repo, huggingface_hub caches the information locally. Next time the user tries to download this file again, we will raise an error directly instead of attempting to make an HTTP call. This saves a few HTTP calls in transformers since the lib is not always aware of which tokenizers files exists on a given repo. This feature exists only when revision is passed with a specific commit_hash.

Since this feature is an optimization, it should be purely optional. That's why we have a try/catch around the file.touch() call to store non-existence of a given file. In huggingface/transformers#33897, @sanketsudake reported that the mkdir call is failing for them with a PermissionError. This PR fixes this by moving it inside the try/catch (PermissionError is a subclass of OSError).

[HuggingFaceDocBuilderDev]

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[hanouticelina]

LGTM!

[Wauplin]

(failing test is unrelated)