bump to 0.6.0

CHANGELOG.md

+## 0.6.0
+* kotlin升级至1.3.21。
+* ios SDK升级至1.8.4。
+* android SDK升级至5.3.6。
+
 ## 0.5.7
 * 修复问题43。
 

pubspec.yaml

 name: fluwx
 description: A implement of WeChatSDK on Flutter.Fluwx makes possible using WeChatSDK in Flutter.Enjoy sharing or payment in Flutter.
-version: 0.5.7
+version: 0.6.0
 author: JarvanMo <jarvan.mo@gmail.com>
 homepage: https://github.com/JarvanMo/fluwx