Disable Python version updates for actions/setup-python from Renovate (#13758)

.github/renovate.json5

@@ -17,6 +17,16 @@
       "description": "Quarterly update of GitHub Action dependencies",
       "schedule": ["every 3 months on the first day of the month"]
     },
+    {
+      // This package rule disables updates for `actions/setup-python` Python versions:
+      // it's better to do these manually as there's often a reason why we can't use
+      // the latest Python version in CI for a specific job
+      groupName: "Python versions",
+      matchManagers: ["github-actions"],
+      matchPackageNames: ["python"],
+      description: "Disable PRs updating Python versions",
+      enabled: false,
+    },
     {
       "groupName": "most test/lint dependencies",
       "matchManagers": ["pip_requirements", "pre-commit"],