build(deps): bump sphinx from 3.5.2 to 3.5.3 (#93)

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[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -13,7 +13,7 @@ pytest-cov>=2.6.1
 pytest-xdist>=1.29.0
 
 # docs
-Sphinx==3.5.2
+Sphinx==3.5.3
 recommonmark==0.7.1
 sphinx-rtd-theme==0.5.1
 sphinx-markdown-tables==0.0.15