model factory rule_stop default to None

Author: Karthikeyannhs

tests/fixtures/builders/model/rule.py

@@ -22,8 +22,7 @@ class IterationCohortFactory(ModelFactory[rules.IterationCohort]): ...
 class IterationRuleFactory(ModelFactory[rules.IterationRule]):
     attribute_target = None
     cohort_label = None
-    rule_stop = False
-
+    rule_stop = None
 
 class IterationFactory(ModelFactory[rules.Iteration]):
     iteration_cohorts = Use(IterationCohortFactory.batch, size=2)