Don't trigger mypy_primer from commits created by pre-commit.ci (#6385)

If pre-commit makes a change immediately after a PR has been made, it's important that the stubtest/mypy/pytype/pyright checks are run again, as line numbers might have changed. However, there's no reason to start a new run of mypy_primer, since pre-commit will make no substantive changes to a PR, only cosmetic changes, and that shouldn't affect the diff from mypy_primer.

.github/workflows/mypy_primer.yml

@@ -11,6 +11,7 @@ on:
 jobs:
   mypy_primer:
     name: Run
+    if: github.actor != 'pre-commit-ci[bot]'
     runs-on: ubuntu-latest
     permissions:
       contents: read