Revert to Python 3.11 for coverage for now

Author: avandras

.github/workflows/tests.yaml

@@ -53,7 +53,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: 3.13
+        python-version: 3.11
 
     - name: Combine coverage
       run: python .github/workflows/run_tests.py combine