Bump requests from 2.5.1 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.5.1 to 2.20.0.
- [Release notes](https://github.com/requests/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/master/HISTORY.md)
- [Commits](https://github.com/requests/requests/compare/v2.5.1...v2.20.0

)

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