Merge branch 'ab/ci-use-macos-12' into maint-2.38

CI fix. * ab/ci-use-macos-12: CI: upgrade to macos-12, and pin OSX version

Junio C Hamano committed Dec 10, 2022 at 14:02 UTC 75efbc1372e27155a2607fd0e8e559e0a020a842

No changes.