ci: explicitly checks macos-14 and macos-15

Author: Ki-Seki

.github/workflows/python-tests.yml

@@ -26,7 +26,9 @@ jobs:
         os:
           - "ubuntu-latest"
           - "windows-latest"
-          - "macos-latest"
+          - "macos-14"
+          - "macos-15"
+          # Ref: https://docs.github.com/en/actions/how-tos/writing-workflows/choosing-where-your-workflow-runs/choosing-the-runner-for-a-job
         python-version:
           - "3.10"
           - "3.11"