Cleanup untagged Docker images

[benoit74]

Docker images keeps pilling up in the GHCR, since we have no solution to clean them up.

We should probably implement https://github.com/vlaurin/action-ghcr-prune to automatically clean the untagged images at the end of each run of the PublishDevDockerImage workflow.

[rgaudin]

Strongly in favor. We should also apply it to non-bootstrap projects

[benoit74]

Of course, I've just opened the issue here first to ensure we are aligned before deploying the approach in the wild ^^