Container Registry: old images are not preserved

Currently, old container images except 161 and 162 are not preserved on registry.salsa.debian.org/reproducible-builds/diffoscope: https://salsa.debian.org/reproducible-builds/diffoscope/container_registry/218

The CI script seems only pushing to the latest tag: https://salsa.debian.org/reproducible-builds/diffoscope/-/blob/232/.gitlab-ci.yml#L78