Bump requests from 2.7.0 to 2.20.0 in /requirements

Bumps [requests](https://github.com/psf/requests) from 2.7.0 to 2.20.0.
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.7.0...v2.20.0)

---
updated-dependencies:
- dependency-name: requests
  dependency-type: direct:production
...

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

requirements/basic.txt

@@ -22,7 +22,7 @@ python-msspeak==0.1.3
 django==1.7.7
 gunicorn==19.3.0
 tablib==0.10.0
-requests==2.7.0
+requests==2.20.0
 lockfile==0.10.2
 librabbitmq==1.6.1
 six==1.9.0