Bump mypy from 0.790 to 0.910

Bumps [mypy](https://github.com/python/mypy) from 0.790 to 0.910.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.790...v0.910)

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

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

Author: dependabot[bot]

requirements-test.txt

@@ -4,4 +4,4 @@ pytest-cov==2.11.1
 black==20.8b1
 flake8==3.9.2
 isort[pipfile]==5.9.3
-mypy==0.790
+mypy==0.910