Don't rely on YAML format guessing for Python versions

Author: ncoghlan

.github/workflows/test.yml

@@ -37,7 +37,7 @@ jobs:
       fail-fast: false  # Always report results for all targets
       max-parallel: 8
       matrix:
-        python-version: [3.10, 3.11, 3.12, 3.13]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
         # There's no platform specific SDK code, but explicitly check Windows anyway
         os: [ubuntu-20.04, windows-2019]