Fix the quoting for installation from git

Author: AA-Turner

.github/workflows/test.yml

@@ -39,7 +39,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           python -m pip install --upgrade pytest
-          python -m pip install --upgrade Sphinx @ git+https://github.com/sphinx-doc/sphinx
+          python -m pip install "Sphinx @ git+https://github.com/sphinx-doc/sphinx"
 
       - name: Test with pytest
         run: python -m pytest --durations 25