fix: support both terragrunt < 0.67 and >= 0.67

README.md

@@ -322,8 +322,6 @@ To use tofu, set `--program=tofu`. Ensure it is installed first.
 
 To use terragrunt, set `--program=terragrunt`. Ensure it is installed first.
 
-NOTE: only terragrunt versions v0.67 and later are supported.
-
 When `terragrunt` is specified as the program executable, Pug enables "terragrunt mode":
 
 * Modules are detected via the presence of a `terragrunt.hcl` file. (You may want to rename the top-level `terragrunt.hcl` file to something else otherwise it is mis-detected as a module).

internal/task/task.go

@@ -185,7 +185,7 @@ func (f *factory) newTask(spec Spec) (*Task, error) {
 	// TODO: introduce a better way to determine whether terrarunt is in use.
 	// Perhaps use constants for terraform, tofu, and terragrunt.
 	if task.Program == "terragrunt" && f.terragrunt {
-		task.Args = append(task.Args, "--terragrunt-forward-tf-stdout")
+		task.AdditionalEnv = append(task.AdditionalEnv, "TERRAGRUNT_FORWARD_TF_STDOUT=1")
 		task.Args = append(task.Args, "--terragrunt-non-interactive")
 	}
 	return task, nil