[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/abbf8aadf43b4b3186e6d71b91a081... - openstack-tox-docs https://zuul.opendev.org/t/openstack/build/9f6d89b3fa274c35968571e1fe799572 : SUCCESS in 3m 02s - openstack-tox-py27 https://zuul.opendev.org/t/openstack/build/d15044436efe4b789ad2f9fcd12681d1 : SUCCESS in 4m 10s - openstack-tox-py36 https://zuul.opendev.org/t/openstack/build/3a3a3e0df3844bf58e0de55ba49aef87 : SUCCESS in 4m 35s - openstack-tox-py37 https://zuul.opendev.org/t/openstack/build/d4d615c5ad994c7abd326c7cbd6df177 : FAILURE in 4m 25s