Bump mypy from 0.930 to 0.950

Bumps [mypy](https://github.com/python/mypy) from 0.930 to 0.950.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.930...v0.950)

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

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

requirements-test.txt

@@ -1,7 +1,7 @@
 -r requirements.txt
 coveralls~=3.3
 mock~=4.0
-mypy==0.930
+mypy==0.950
 pre-commit~=2.16
 pylint~=2.12
 pylint-strict-informational==0.1