[placement][gate] functional tests failing

Hi all, I recently proposed a change to openstack/placement and found that the functional tests are currently failing. It's because of a recent-ish bump to upper-constraints to allow os-traits 2.4.0: https://review.opendev.org/739330 and placement has a func test that asserts the number of standard traits (more traits are available in 2.4.0). I've proposed a fix for the func test here if anyone could please help review: https://review.opendev.org/744790 Cheers, -melanie