bump to v3.4.0

CHANGELOG.md

+## 3.4.0
+* 修复从外部拉起App白屏问题
+* 修复从外部拉起App无法传值问题
+
 ## 3.3.2
 * Fix #357
 

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: 3.3.3
+version: 3.4.0
 homepage: https://github.com/JarvanMo/fluwx
 
 environment: