Need to be able to set the network=host driver opt to use a local registry

[Cluster444]

Running a private docker registry on the same host that the build & deploy are running will fail as the buildx container can't reach it.

To get it to work I had to drop the buildx container and recreate it with --driver-opt network=host and then it was able to see my registry, push the image as well as the cache layers.

Not sure if there is another way to get the build container to see the registry, or if kamal needs to allow that option in the builder create command.