Bump sphinx from 3.5.2 to 3.5.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.2 to 3.5.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](https://github.com/sphinx-doc/sphinx/commits)

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

Author: dependabot-preview[bot]

dev-requirements.txt

@@ -1,6 +1,6 @@
 PyYAML==5.4.1
 Sphinx-Substitution-Extensions==2020.9.30.0
-Sphinx==3.5.2
+Sphinx==3.5.3
 VWS-Test-Fixtures==2020.9.25.1
 autoflake==1.4
 black==20.8b1