Bump mypy from 0.902 to 0.961

Bumps [mypy](https://github.com/python/mypy) from 0.902 to 0.961.
- [Release notes](https://github.com/python/mypy/releases)
- [Commits](python/mypy@v0.902...v0.961)

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

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

Author: dependabot[bot]

setup.py

@@ -68,7 +68,7 @@
         'doc8',
         'flake8',
         'invoke',
-        'mypy==0.902',
+        'mypy==0.961',
         'nox',
         "pytest>=4.6",
         'pytest-cov',
@@ -80,7 +80,7 @@
     ],
     'validate': [
         'flake8',
-        'mypy==0.902',
+        'mypy==0.961',
         'types-pkg-resources',
     ],
 }