优化代码，删除无效代码

plugins/plugin_manager/main.py

@@ -37,6 +37,18 @@ class PluginManagerPlugin(MessagePluginInterface):
     def commands(self) -> List[str]:
         return self._commands
 
+    def start(self) -> bool:
+        """启动插件"""
+        self.LOG.info(f"[{self.name}] 插件已启动")
+        self.status = PluginStatus.RUNNING
+        return True
+
+    def stop(self) -> bool:
+        """停止插件"""
+        self.LOG.info(f"[{self.name}] 插件已停止")
+        self.status = PluginStatus.STOPPED
+        return True
+
     def __init__(self):
         super().__init__()
         self.bot: WechatAPIClient = None