Bump sphinx from 4.0.3 to 4.1.0

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 4.0.3 to 4.1.0.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/4.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v4.0.3...v4.1.0)

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

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

Author: dependabot[bot]

requirements_dev.txt

@@ -8,7 +8,7 @@ pip
 pytest-runner==5.3.1
 pytest==6.2.4
 recommonmark==0.7.1
-Sphinx==4.0.3
+Sphinx==4.1.0
 twine==3.4.1
 types-Jinja2==2.11.2
 types-pkg_resources==0.1.3