Bump requests from 2.18.4 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.18.4 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@v2.18.4...v2.20.0)

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

Author: dependabot[bot]

requirements.txt

@@ -30,7 +30,7 @@ Pygments==2.2.0
 pytest==3.5.0
 pytest-cov==2.5.1
 PyYAML==3.12
-requests==2.18.4
+requests==2.20.0
 six==1.11.0
 urllib3==1.22
 virtualenv==15.2.0