Bump mypy from 0.930 to 0.931 (#259)

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:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

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

Author: dependabot[bot]

poetry.lock

@@ -59,7 +59,7 @@ typing_extensions = ">=3.6,<5"
 [tool.poetry.dev-dependencies]
 django = "^3.2"
 
-mypy = "^0.930"
+mypy = "^0.931"
 wemake-python-styleguide = "^0.16"
 flake8-pytest-style = "^1.5"
 nitpick = "^0.29"