Bump requests from 2.19.1 to 2.20.0

Bumps [requests](https://github.com/psf/requests) from 2.19.1 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@v2.19.1...v2.20.0)

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

requirements.txt

@@ -10,7 +10,7 @@ itsdangerous==0.24
 Jinja2==2.10
 MarkupSafe==1.1.1
 pyasn1==0.4.3
-requests==2.19.1
+requests==2.20.0
 urllib3==1.23
 Werkzeug==0.14.1
 zope.event==4.5.0