py-requests: updated to 2.20.0

2.20.0:
Bugfixes
Content-Type header parsing is now case-insensitive (e.g. charset=utf8 v Charset=utf8).
Fixed exception leak where certain redirect urls would raise uncaught urllib3 exceptions.
Requests removes Authorization header from requests redirected from https to http on the same hostname. (CVE-2018-18074)
should_bypass_proxies now handles URIs without hostnames (e.g. files).

Dependencies
Requests now supports urllib3 v1.24.

Deprecations
Requests has officially stopped support for Python 2.6.

(adam)