Bump sphinx from 3.5.0 to 3.5.1

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.0 to 3.5.1.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/3.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.5.0...v3.5.1)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

requirements.txt

@@ -1,6 +1,6 @@
 -i https://pypi.org/simple/
 
-sphinx==3.5.0
+sphinx==3.5.1
 sphinx-tabs==2.0.1
 sphinxemoji==0.1.8
 sphinx-rtd-theme==0.5.1