Bump mypy from 0.782 to 0.790 (#245)

Bumps [mypy](https://github.com/python/mypy) from 0.782 to 0.790.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](https://github.com/python/mypy/compare/v0.782...v0.790)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>
Co-authored-by: Pierre Ståhl <pierre.staahl@gmail.com>

requirements_test.txt

@@ -1,7 +1,7 @@
 black==20.8b1
 codespell==2.0.0
 flake8==3.8.4
-mypy==0.782
+mypy==0.790
 pydocstyle==5.1.1
 cryptography==3.2
 pylint==2.6.0