Bump Python version for integration tests

Some packages like ``sphinx`` already started dropping support for Python 3.8.

Author: abravalheri

.github/workflows/main.yml

@@ -217,7 +217,7 @@ jobs:
         uses: actions/setup-python@v4
         with:
           # Use a release that is not very new but still have a long life:
-          python-version: "3.8"
+          python-version: "3.10"
       - name: Install tox
         run: |
           python -m pip install tox