build: 更新 six-shop/core 依赖并修改扩展类路径

-将 six-shop/core 依赖从0.5.7 版本升级到 0.5.8 版本
- 修改扩展类路径从 "SixShop\\News" 到 "SixShop\\News\\Extension"

composer.json

@@ -8,7 +8,7 @@
   ],
   "require": {
     "php": ">=8.3",
-    "six-shop/core": ">=0.5.7 <1.0"
+    "six-shop/core": ">=0.5.8 <1.0"
   },
   "authors": [
     {
@@ -25,7 +25,7 @@
   "extra": {
     "sixshop": {
       "id": "message",
-      "class": "SixShop\\News"
+      "class": "SixShop\\News\\Extension"
     }
   },
   "minimum-stability": "dev",