fixes broadcasted changes from deep flattening empty array attributes

Author: adamcreekroad

lib/reactive_record/broadcast.rb

@@ -215,7 +215,7 @@ def merge_current_values(br)
           return nil
         end
         [attr, value]
-      end.compact.flatten]
+      end.compact.flatten(1)]
       # TODO: verify - it used to be current_values.merge(br.attributes)
       klass._react_param_conversion(br.attributes.merge(current_values))
     end