chore(deps-dev): bump sphinx from 4.0.2 to 4.0.3

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 4.0.2 to 4.0.3.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/4.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v4.0.2...v4.0.3)

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

dev-requirements.txt

@@ -4,7 +4,7 @@ coveralls==2.2.0
 pytest==6.2.4
 pytest-cov==2.12.1
 attrs~=21.2.0
-Sphinx==4.0.2
+Sphinx==4.0.3
 sphinx-bootstrap-theme==0.7.1
 sphinxcontrib-fulltoc==1.2.0
 sphinxcontrib-websupport==1.2.4