With provider 1.54 the plan replaces both servers. Hetzner stopped
returning a server's datacenter, the old provider derived the location
from it, and a location that reads back empty differs from "hel1",
which forces replacement. Only prevent_destroy stood in the way.
Provider 1.70.2 reads the location properly: the same plan then shows
the two firewall updates and nothing else. The lock file is not
tracked, so raise the version constraint to keep the old provider out.
Run terraform init -upgrade once in existing checkouts.
Assisted-by: Claude:fable-5-2
