CI: Timeout tox and dump debug information if we go >20 minutes

Author: effigies

.github/workflows/stable.yml

@@ -150,7 +150,7 @@ jobs:
       - name: Show tox config
         run: pipx run tox c
       - name: Run tox
-        run: tox
+        run: tox --exit-and-dump-after 1200
       - uses: codecov/codecov-action@v3
         if: ${{ always() }}
         with: