bump to 4.2.4

CHANGELOG.md

+# 4.2.4
+* 修复iOS extMsg的问题
+
 # 4.2.3
 * 修复iOS冷启动extMsg的问题
 

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: 4.2.3
+version: 4.2.4
 homepage: https://github.com/OpenFlutter/fluwx
 
 environment: