[llvm] [CI][format] Explicitly pass extensions to git-clang-format (take 2) (PR #98227)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

One other thing to note (if you aren't already aware) is that the python scripts are pulled in from `main` rather than the branch being merged in, so you need to modify this step if you want to test changes in the branch to the python utilities:
https://github.com/llvm/llvm-project/blob/f35318e828d166bee04a117c1a87c1c0e32a57da/.github/workflows/pr-code-format.yml#L37

https://github.com/llvm/llvm-project/pull/98227