fix: Fix import function lib permission

--bug=1052409 --user=刘瑞斌 【函数库】导入一个原来是公有的函数，函数的权限依然是公有 https://www.tapd.cn/57709429/s/1658705

apps/function_lib/serializers/function_lib_serializer.py

@@ -274,7 +274,7 @@ class FunctionLibSerializer(serializers.Serializer):
                                              code=function_lib.get('code'),
                                              user_id=user_id,
                                              input_field_list=function_lib.get('input_field_list'),
-                                             permission_type=function_lib.get('permission_type'),
+                                             permission_type='PRIVATE',
                                              is_active=function_lib.get('is_active'))
             function_lib_model.save()
             return True