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)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

setup.py

@@ -10,7 +10,7 @@
         "pre-commit~=2.4",
     ],
     "docs": [
-        "sphinx==4.0.2",
+        "sphinx==4.0.3",
         "sphinx-issues==1.2.0",
         "alabaster==0.7.12",
         "sphinx-version-warning==1.1.2",