Bump requests from 2.4.3 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.4.3 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/v2.4.3...v2.20.0)

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

requirements.txt

@@ -1,3 +1,3 @@
 gevent==1.0.1
 msgpack-python==0.4.2
-requests==2.4.3
+requests==2.20.0