Bump mypy from 0.921 to 0.930 in /docs (#1190)

Bumps [mypy](https://github.com/python/mypy) from 0.921 to 0.930.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.921...v0.930)

---
updated-dependencies:
- dependency-name: mypy
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

Author: dependabot[bot]

docs/requirements.txt

@@ -13,7 +13,7 @@ pygments==2.10.0
 
 # Dependencies of our project:
 typing-extensions==4.0.1
-mypy==0.921
+mypy==0.930
 pytest==6.2.5
 hypothesis==6.32.1