fix(ci): unpin Python patch versions in test matrix

Python 3.13.2's `VERIFY_X509_STRICT` rejects some certifi CA certs,
breaking `httpx.Client()` init. Using minor-only versions lets
setup-python resolve to latest patches automatically.

Author: parfeon

.github/workflows/run-tests.yml

@@ -26,7 +26,7 @@ jobs:
       max-parallel: 1
       fail-fast: true
       matrix:
-        python: [3.9.21, 3.10.16, 3.11.11, 3.12.9, 3.13.2]
+        python: ["3.9", "3.10", "3.11", "3.12", "3.13"]
     timeout-minutes: 5
     steps:
       - name: Checkout repository