Bump sphinx from 3.2.1 to 3.3.0

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.2.1 to 3.3.0.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.2.1...v3.3.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements.txt

@@ -10,5 +10,5 @@ gunicorn==20.0.4
 pycodestyle==2.6.0
 pydocstyle==5.1.1
 requests==2.24.0
-Sphinx==3.2.1
+Sphinx==3.3.0
 Werkzeug==1.0.1