Fix linter issue

Author: IvanBM18

src/clusterfuzz/_internal/system/environment.py

@@ -1240,4 +1240,4 @@ def is_tworker():
 
 def is_running_unit_tests() -> bool:
   """Returns whether or not we're running unit tests."""
-  return get_value('PY_UNITTESTS', False)
+  return get_value('PY_UNITTESTS', False)