update: 修复重复的回调类

Runtime/GuruCore/Runtime/Common/GuruSDKCallback.cs

@@ -72,14 +72,5 @@ namespace Guru
             Instance.msgCallback -= callback;
         }
 
-        /// <summary>
-        /// 添加回调
-        /// </summary>
-        /// <param name="callback"></param>
-        public static void RemoveCallback(Action<string> callback)
-        {
-            Instance.SubCallback(callback);
-        }
-
     }
 }