[all] POST_FAILURE in openstack-tox-py310

I feel like this week is one of the most exciting week we have had recently :-P We started seeing consistent POST_FAILURE in openstack-tox-py310 (and other jobs using py310). https://github.com/testing-cabal/testtools/issues/569 The issue was caused by testtools and was fixed in testools 2.8.4, but we likely need to rebuild the image used in CI to pull the fixed version. Please avoid mass recheck or merging any new changes now before you check the CI status carefully. Thank you, Takashi -- Takashi Kajinami irc: tkajinam github: https://github.com/kajinamit launchpad: https://launchpad.net/~kajinamit