Upgrade appleclang14 build to MacOS 13

> The macOS-12 environment is deprecated, consider switching to macOS-13,
macOS-14 (macos-latest) or macOS-15. For more details, see
actions/runner-images#10721

Author: franzpoeschel

.github/workflows/macos.yml

@@ -45,7 +45,7 @@ jobs:
         ctest --test-dir build --verbose
 
   appleclang14_py:
-    runs-on: macos-12
+    runs-on: macos-13
     if: github.event.pull_request.draft == false
     steps:
     - uses: actions/checkout@v4