This container can be pulled via:
  docker pull registry.opensuse.org/opensuse/leap/15.3/images/totest/containers/opensuse/leap-microdnf:15.3
  docker pull registry.opensuse.org/opensuse/leap/15.3/images/totest/containers/opensuse/leap-microdnf:15.3.2.251

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.