Bump mypy from 0.770 to 0.780

Bumps [mypy](https://github.com/python/mypy) from 0.770 to 0.780.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.770...v0.780)

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

Author: dependabot[bot]

requirements.txt

@@ -1,3 +1,3 @@
 asserts==0.10.0
-mypy==0.770
+mypy==0.780
 wheel==0.34.2