The provider source moved from git.unkin.net/unkin/artifactapi to
artifactapi.k8s.syd1.au.unkin.net/terraform-unkin/artifactapi. .terraform.lock.hcl
is gitignored, so a CI runner reusing a workspace/cache keeps a lock pinning the
old source; some OpenTofu versions then try to re-resolve git.unkin.net (which
isn't a registry) instead of dropping it, failing init.
Delete any .terraform.lock.hcl before `terragrunt run --all init -- -upgrade` so
providers resolve purely from config.