[CI] Style checks are broken

[AThousandShips]

Tested versions

N/A

System information

N/A

Issue description

Code style checks are no longer being applied, see for example:
82f5bd6

Seems to be a regression from:

• CI: Overhaul static checks to use pre-commit #91597

All checks are now marked as skipped and claims there are no files to check

Steps to reproduce

N/A

Minimal reproduction project (MRP)

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[AThousandShips]

CC @Repiteo @akien-mga

[akien-mga]

Indeed the new code run pre-commit run --verbose, and by default pre-commit run only affects files which have been staged in Git. In a PR or merge CI run, there's no staged files, as the commit was already made. So we still need a way to pass the list of files changed in the commit(s) compared to the base branch.

So we should probably restore the --files ${{ env.CHANGED_FILES }} logic, unless the pre-commit action provides a facility for this. (I suppose it doesn't, the action repo says it's in maintenance mode and they encourage us to use their own hosted CI system.)

[fire]

Do we need to fork our own https://github.com/pre-commit/action that avoids a hosted ci system?

[akien-mga]

Do we need to fork our own https://github.com/pre-commit/action that avoids a hosted ci system?

No, that action is a GitHub Action and is therefore "hosted"/run by GitHub in the runners they provide us.
The "pre-commit CI" they mention is a separate, bespoke product that they offer. We don't have to use it is the basic GH action works for us.