docker image tag latest should rather point to the latest *release*

[lelutin]

Currently on docker hub the karma docker image is tagged with the different versions and there's a latest tag but the project recommends against using it for production since that tag contains the latest commit on the main branch.

This means that I currently need to hardcode the version tag and can't use auto-upgrade to stay on the latest release.

Usually the tag named latest is just a pointer to the latest release. So I would propose that the docker image publication tasks be changed so that when a new release is made, the latest tag is changed to point to that new release instead.

there could still be a tag that points to the latest commit, named for example nightly