collabora: ci: Tag Docker image as "latest" as well
This change does not increase Container Registry storage usage because image layers stored there are deduplicated at the root namespace level [0].
Purpose of this convenience feature is to support such use cases where image tag might not be known up front (unlike CI or Ansible-based deployments), e.g. default values for the Helm chart.
Signed-off-by: Paweł Wieczorek pawiecz@collabora.com