chore(deps-dev): bump pytype from 2020.7.14 to 2020.7.20 (#7151)

Bumps [pytype](https://github.com/google/pytype) from 2020.7.14 to 2020.7.20.
- [Release notes](https://github.com/google/pytype/releases)
- [Changelog](https://github.com/google/pytype/blob/master/CHANGELOG)
- [Commits](google/pytype@2020.07.14...2020.07.20)

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

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

Author: dependabot-preview[bot]

requirements/dev.txt

@@ -6,4 +6,4 @@ pep8==1.7.1
 isort==5.1.4
 black==19.10b0
 pre-commit==2.6.0
-pytype==2020.7.14
+pytype==2020.7.20