Bump mypy from 0.930 to 0.931

Bumps [mypy](https://github.com/python/mypy) from 0.930 to 0.931.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.930...v0.931)

---
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.txt

@@ -1,3 +1,3 @@
 asserts==0.11.1
-mypy==0.930
+mypy==0.931
 wheel==0.37.1