Bump requests from 2.9.1 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.9.1 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/v2.9.1...v2.20.0)

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

requirements.txt

@@ -1,4 +1,4 @@
-requests==2.9.1
+requests==2.20.0
 jsonpickle==0.7.1
 cachecontrol==0.11.7
 python-dateutil==2.5.3