Glance isn't explicitly installing requirements, so add requirements
as tox deps in such a way that they'll be properly constrained by the
current openstack upper-constraints.
This change also bumps the version of psycopg to that of the current
upper-constraints in test-requirements and lower-constraints. (The
version in our current lower-constraints is subject to the "could not
determine PostgreSQL version from '10.x'" error, which causes the
lower-constraints job to fail.)