www/py-requests: Allow urllib3 1.22 dependency

• Backport an upstream patch to setup.py allowing urllib3 1.22 dependency
• Bump PORTREVISION

PR: 220927
Submitted by: cpm
Reported by: P. Chevalier<chevalier@dspnet.fr>
Reviewed by: jbeich, koobs
Approved by: koobs (maintainer)
Obtained from: https://github.com/requests/requests/commit/8d1228cd1943bfe89ffaae32e15b2feb3f8479f5