move import into the function

src/cal_tools/restful_config.py

 from pathlib import Path
 
-from calibration_client import CalibrationClient
 from dynaconf import Dynaconf
 
 config_dir = Path(__file__).parent.resolve()
@@ -17,6 +16,8 @@ restful_config = Dynaconf(
 
 
 def calibration_client():
+    from calibration_client import CalibrationClient
+
     # Create client for CalCat.
     calcat_config = restful_config.get('calcat')
     return CalibrationClient(