Bump requests from 2.18.4 to 2.20.0

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -47,7 +47,7 @@ pytz==2018.7
 pyverdict==0.1.3.2
 pyxdg==0.25
 PyYAML==3.12
-requests==2.18.4
+requests==2.20.0
 scikit-learn==0.20.3
 scipy==1.2.1
 SecretStorage==2.3.1