This container can be pulled via:
  docker pull registry.opensuse.org/devel/kubic/containers/container/kubic/etcd:3.5.15-0.14.156
  docker pull registry.opensuse.org/devel/kubic/containers/container/kubic/etcd:3.5.15-1.14.156

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.