Pin test-requirements to match OpenStack requirements
Pin test-requirements to match OpenStack requirements

A new release of flake8 is causing lint faiures. Our requirements
should match OpenStack requirements anyway.

This patch pins to the current master requirements from the
OpenStack requirements repository using global-requirements.

Change-Id: I1f8bc6c83495789faf74382fa901915de54114d5

openstack/openstack-ansible-memcached_server,openstack/openstack-ansible-memcached_server