try macOS tests with v12 Monterey

Author: petercorke

.github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [windows-latest, ubuntu-latest, macos-13]
+        os: [windows-latest, ubuntu-latest, macos-12]
         python-version: ["3.7", "3.8", "3.9", "3.10", "3.11"]
 
     steps: