core (memory/sqla): session_add must have a default value in delete

sat/memory/sqla.py

@@ -223,7 +223,7 @@ class Storage:
         db_cls: DeclarativeMeta,
         db_id_col: Mapped,
         id_value: Any,
-        joined_loads=None
+        joined_loads = None
     ) -> Optional[DeclarativeMeta]:
         stmt = select(db_cls).where(db_id_col==id_value)
         if client is not None:
@@ -248,7 +248,7 @@ class Storage:
     async def delete(
         self,
         db_obj: Union[DeclarativeMeta, List[DeclarativeMeta]],
-        session_add: Optional[List[DeclarativeMeta]]
+        session_add: Optional[List[DeclarativeMeta]] = None
     ) -> None:
         """Delete an object from database