Update CI to MacOS 13 due to GHA deprecation

Author: pimterry

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
           - platform: windows
             os: "windows-2019"
           - platform: mac
-            os: "macos-12"
+            os: "macos-13"
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4