make LlamaModel._update_causal_mask torch compilable

[winglian]

What does this PR do?

This doesn't really have a performance improvement, but at least keeps torch.compile from having a graph break here.

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?

@ArthurZucker
Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

[Rocketknight1]

Hi @winglian, this looks like a good change, but this code is inherited by many other models using # Copied from. You'll need to run make fix-copies to propagate the change to them before the CI will be green!

[winglian]

thanks @Rocketknight1 TIL! changes made!

[Rocketknight1]

cc @ArthurZucker for review - failing test seems unrelated!

[ArthurZucker]

Perfect! thanks for fixing! Let's just rebase and we should merge

[ArthurZucker]

@winglian took the liberty to push the required changes, as I supposed you probably were on holidays! 🎄