refactor: entity not found exceptions handler

modules/fulfillment_base/repositories/services_kit.py

@@ -12,6 +12,7 @@ class ServicesKitRepository(
     RepCrudMixin[ServicesKit, CreateServicesKitSchema, UpdateServicesKitSchema],
 ):
     entity_class = ServicesKit
+    entity_not_found_msg = "Набор услуг не найден"
 
     def _process_get_by_id_stmt(self, stmt: Select) -> Select:
         return stmt.options(selectinload(ServicesKit.services))