升级topon sdk版本2.1.5， 升级平台插件版本至最新

AnyThinkPlugin/AnyThinkAds/Platform/iOS/Internal/C/ATUnitySafeThreadDictionary.h

@@ -0,0 +1,22 @@
+//  ATSafeThreadDictionary.h
+//  ATSDK
+//
+//  Created by topon on 2020/9/21.
+//  Copyright © 2020 AnyThink. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+/**
+ A simple implementation of thread safe mutable dictionary.
+ 
+ @discussion Generally, access performance is lower than NSMutableDictionary,
+ but higher than using @synchronized, NSLock, or pthread_mutex_t.
+ 
+ @warning Fast enumerate(for...in) and enumerator is not thread safe,
+ use enumerate using block instead. When enumerate or sort with block/callback,
+ do *NOT* send message to the dictionary inside the block/callback.
+ */
+@interface ATUnitySafeThreadDictionary<KeyType, ObjectType> : NSMutableDictionary
+
+@end