CI failing due to `mistralai/Mistral-7B-Instruct-v0.2` being gated now

[alvarobartt]

Description

Since recently Mistral marked their repository at https://huggingface.co/mistralai/Mistral-7B-Instruct-v0.2 as a gated repository, I'm afraid that the account using the HF_TOKEN set as a secret for the CI will need to accept the Mistral AI conditions to be able to access the gated repository.

I believe that simply clicking the Agree and access repository button for that model will do the work! Alternatively, another tokenizer can be used instead to avoid using a gated repository for the unit tests.

cc @lewtun @kashif