Merge PR rocq-prover#18587: CI: use macos 12 instead of 11

Reviewed-by: herbelin
Co-authored-by: herbelin <[email protected]>

Author: coqbot-app[bot]

.github/workflows/ci-macos.yml

@@ -7,7 +7,7 @@ permissions:
 
 jobs:
   macOS:
-    runs-on: macos-11
+    runs-on: macos-12
 
     steps:
       - uses: actions/checkout@v3