CI fails to deploy to master because it does not push built images to dockerhub

[pcrespov]

Last commit deployed in master is eeaf834

If we look now in dockerhub. Notice how, as expected, the tags change for each commit but the digest remains the same! Try for instance with https://hub.docker.com/r/itisfoundation/autoscaling/tags?page=1&name=master

My guess is that the problem must be in the ♻️ CI build times: leverage docker buildx github registry caching and transmit builds to int/sys tests (#3369) (3a93ebb).

Somehow the new images do not get pushed to github and therefore it deploys always the same which was simply retagged