Fix Python version to 3.11

Author: MathiasMagnus

.github/workflows/macos.yml

@@ -320,6 +320,12 @@ jobs:
             ;;
           esac
 
+      - name: Set up Python 3.11
+        if: matrix.options.py == 'ON' && matrix.check_mkvk != 'ONLY'
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11.4'
+
       - name: before_script
         run: |
           case "${RUNNER_OS:-Linux}" in