Create a "324" gcloud image to workaround bug in latest version
This is a workaround for https://issuetracker.google.com/issues/178510874
Additionally, move to building gcloud-docker weekly in order to potentially avoid day-0 bugs.
Closes #46 (closed) As part of https://gitlab.developers.cam.ac.uk/uis/devops/iam/deploy-identity/-/issues/28