Bumps [pytype](https://github.com/google/pytype) from 2020.2.20 to 2020.8.28.
- [Release notes](https://github.com/google/pytype/releases)
- [Changelog](https://github.com/google/pytype/blob/master/CHANGELOG)
- [Commits](https://github.com/google/pytype/compare/2020.02.20...2020.08.28)
Signed-off-by: Ndependabot[bot] <support@github.com>