Fix pipeline

run sphinx-latest only when Python version is higher than 3.9

Author: JokeWaumans

.github/workflows/python-package.yml

@@ -23,6 +23,7 @@ jobs:
     - name: Build documentation with Sphinx 2.4.5
       run: tox -e sphinx2.4.5
     - name: Build documentation with latest Sphinx versions
+      if: matrix.python-version > 3.9
       run: tox -e sphinx-latest
     - name: Static checks
       if: matrix.python-version == 3.9