Remove an unused config import (#3757)

# Changed Behaviour

none

## Type of change

- Code maintenance/cleanup

Author: benclifford

parsl/tests/test_python_apps/test_memoize_1.py

@@ -2,7 +2,6 @@
 
 import parsl
 from parsl.app.app import python_app
-from parsl.tests.configs.local_threads import config
 
 
 @python_app(cache=True)