build(deps): bump sphinx from 3.5.4 to 4.3.2 (#138)

Bumps [sphinx](https://github.com/sphinx-doc/sphinx) from 3.5.4 to 4.3.2.
- [Release notes](https://github.com/sphinx-doc/sphinx/releases)
- [Changelog](https://github.com/sphinx-doc/sphinx/blob/5.x/CHANGES)
- [Commits](sphinx-doc/sphinx@v3.5.4...v4.3.2)

---
updated-dependencies:
- dependency-name: sphinx
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

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

docs/requirements.txt

@@ -1,4 +1,4 @@
 py-moneyed==1.2
-sphinx==3.5.4
+sphinx==4.3.2
 sphinx-autodoc-typehints==1.12.0
 sphinx-rtd-theme==0.5.2