Added bool to type hint for 'on' function in Joiner

Author: mcsj120

pypika/queries.py

@@ -1618,7 +1618,7 @@ def __init__(
         self.how = how
         self.type_label = type_label
 
-    def on(self, criterion: Optional[Criterion], collate: Optional[str] = None) -> QueryBuilder:
+    def on(self, criterion: Optional[Union[Criterion, bool]], collate: Optional[str] = None) -> QueryBuilder:
         if criterion is None:
             raise JoinException(
                 "Parameter 'criterion' is required for a "