refactor(backend): 修改 news扩展的标识符

-将 composer.json 文件中的 "id" 值从 "message" 修改为 "news"
- 此修改有助于更准确地反映扩展的功能和用途

composer.json

@@ -24,7 +24,7 @@
   },
   "extra": {
     "sixshop": {
-      "id": "message",
+      "id": "news",
       "class": "SixShop\\News\\Extension"
     }
   },