[Openstack-stable-maint] Stable check of openstack/oslo.serialization for ref refs/heads/stable/train failed

Build failed. https://zuul.opendev.org/t/openstack/buildset/991a9f4964db4780928ad75fa946f4... - openstack-tox-docs https://zuul.opendev.org/t/openstack/build/132889b7cc8f4c33bd807adfe653127a : SUCCESS in 4m 13s - openstack-tox-py27 https://zuul.opendev.org/t/openstack/build/73ae3d0f9b4746ca917af9f1939bc502 : SUCCESS in 4m 09s - openstack-tox-py36 https://zuul.opendev.org/t/openstack/build/c7a19cdc3ed4469384bd21250b4c84d2 : SUCCESS in 3m 44s - openstack-tox-py37 https://zuul.opendev.org/t/openstack/build/a9025b79b7fc4dc8b897c3d506f07520 : FAILURE in 4m 28s