update version to 8.2.0

Author: YangSen-qn

QiniuSDK/Utils/QNVersion.h

@@ -11,4 +11,4 @@
 /**
  *    sdk 版本
  */
-static NSString *const kQiniuVersion = @"8.1.2";
+static NSString *const kQiniuVersion = @"8.2.0";