Prepare for necessary move to macOS 13

GH will remove macOS 12 runner images as of December 3rd, so we prepare
for that.

Author: cmb69

.github/workflows/push.yml

@@ -97,7 +97,7 @@ jobs:
         uses: ./.github/actions/verify-generated-files
   MACOS_DEBUG_NTS:
     if: github.repository == 'php/php-src' || github.event_name == 'pull_request'
-    runs-on: macos-12
+    runs-on: macos-13
     steps:
       - name: git checkout
         uses: actions/checkout@v4