[Security] Bump requests from 2.18.4 to 2.20.1

Bumps [requests](https://github.com/requests/requests) from 2.18.4 to 2.20.1. **This update includes security fixes.**
- [Release notes](https://github.com/requests/requests/releases)
- [Changelog](https://github.com/requests/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.18.4...v2.20.1)

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

Author: dependabot-support

Pipfile

@@ -13,7 +13,7 @@ chardet = "==3.0.4"
 docopt = "==0.6.2"
 idna = "==2.6"
 numpy = "==1.13.3"
-requests = "==2.18.4"
+requests = "==2.20.1"
 scikit-learn = "==0.19.1"
 scipy = "==1.0.0"
 "urllib3" = "==1.22"