Add test run on other OS

Author: znicholls

.github/workflows/ci.yaml

@@ -76,6 +76,19 @@ jobs:
         os: [ "ubuntu-latest" ]
         # Test against all security and bugfix versions: https://devguide.python.org/versions/
         python-version: [ "3.9", "3.10", "3.11", "3.12", "3.13" ]
+        include:
+          # Test other OS's for a 'very stable' Python version too
+          - os: "windows-latest"
+            python-version: "3.11"
+          - os: "macos-latest"
+            python-version: "3.11"
+          # Include other OS for latest Python
+          # because these seem to be the flakiest from experience
+          # so are worth the extra testing
+          - os: "windows-latest"
+            python-version: "3.13"
+          - os: "macos-latest"
+            python-version: "3.13"
     runs-on: "${{ matrix.os }}"
     defaults:
       run: