[all][requirements][stable] requests version bump on stable brances {pike|queens} for CVE-2018-18074

Hi all, This is a warning and call to test the requests updates linked below. The best way to test is to make a dummy review in your project that depends on the linked review (either Pike or Queens). Upstream has no intrest or (easy) ability to backport the patch. Please let us know either in the the #openstack-requirements channel or in this email thread if you have issues. Pike - 2.18.2 -> 2.20.1 - https://review.opendev.org/640727 Queens - 2.18.4 -> 2.20.1 - https://review.opendev.org/640710 -- Matthew Thode