优化代码，删除无效代码

plugins/global_news/main.py

@@ -3,7 +3,6 @@ import threading
 import time  # 添加这一行
 from typing import Dict, Any, List, Optional, Tuple
 
-from message_util import MessageUtil
 from plugin_common.message_plugin_interface import MessagePluginInterface
 from plugin_common.plugin_interface import PluginStatus
 from utils.decorator.plugin_decorators import plugin_stats_decorator
@@ -56,7 +55,6 @@ class GlobalNewsPlugin(MessagePluginInterface):
 
         # 保存上下文对象
         self.event_system = context.get("event_system")
-        self.message_util: MessageUtil = context.get("message_util")
 
         self._commands = self._config.get("GlobalNews", {}).get("command",
                                                                 ["全球新闻", "国际新闻", "环球新闻", "政经新闻"])