bump to 4.3.1

CHANGELOG.md

+# 4.3.1
+* Merge #574
+
 # 4.3.0
 * Android minSdkVersion升级至19
 * 主要解决了 iOS 端的冷启动参数传递问题

pubspec.yaml

 name: fluwx
 description: The capability of implementing WeChat SDKs in Flutter. With Fluwx, developers can use WeChatSDK easily, such as sharing, payment, lanuch mini program and etc.
-version: 4.3.0
+version: 4.3.1
 homepage: https://github.com/OpenFlutter/fluwx
 
 environment: