Bump requests from 2.3.0 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.3.0 to 2.20.0.
- [Release notes](https://github.com/requests/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.3.0...v2.20.0)

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

requirements.txt

@@ -1,4 +1,4 @@
 beautifulsoup4==4.3.2
 GitPython==0.3.6
-requests==2.3.0
+requests==2.20.0
 six==1.9.0