copy_config: fix import

scripts/copy_config.py

@@ -10,10 +10,11 @@ from pathlib import Path
 from shutil import copy
 
 import yaml
+from _helpers import set_scenario_config
 
 if __name__ == "__main__":
     if "snakemake" not in globals():
-        from _helpers import mock_snakemake, set_scenario_config
+        from _helpers import mock_snakemake
 
         snakemake = mock_snakemake("copy_config")