Bump sphinx from 3.5.4 to 4.0.2 (#44)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.4 to 4.0.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/4.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.5.4...v4.0.2)

Signed-off-by: dependabot[bot] <[email protected]>

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

Author: dependabot[bot]

poetry.lock

@@ -55,7 +55,7 @@ mypy = "^0.812"
 pytest-mypy = "^0.8.1"
 pytest-mock = "^3.5.1"
 hypothesis = "^6.13.5"
-Sphinx = "^3.5.3"
+Sphinx = "^4.0.2"
 sphinx-rtd-theme = "^0.5.2"
 sphinx-autobuild = "^2021.3.14"
 line-profiler = "^3.2.6"