Renovate: auto-update container image when it is updated.
Configure renovate to track the container digest and update it automatically, when the digest changes.
Whenever the Debian bookworm gets a security update, then we want to update the container that is being used.
In order to do that:
- set the current digest of the current container image in the registry
- configure renovate to track docker digests
- configure renovate to auto-merge docker digest changes if they are from our registry
- configure renovate to not auto-merge docker digest changes otherwise