Bump sphinx from 3.4.3 to 3.5.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.4.3 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] <[email protected]>

Author: dependabot-preview[bot]

docs-requirements.txt

@@ -34,7 +34,7 @@ requests==2.25.1
     # via sphinx
 snowballstemmer==2.1.0
     # via sphinx
-sphinx==3.4.3
+sphinx==3.5.3
     # via -r docs-requirements.in
 sphinxcontrib-applehelp==1.0.2
     # via sphinx

test-requirements.txt

@@ -60,7 +60,7 @@ requests==2.25.1
     # via sphinx
 snowballstemmer==2.1.0
     # via sphinx
-sphinx==3.4.3
+sphinx==3.5.3
     # via -r test-requirements.in
 sphinxcontrib-applehelp==1.0.2
     # via sphinx