bump to 4.2.1

CHANGELOG.md

+# 4.2.1
+* 支持选用scene_delegate.
+
 # 4.2.0
 * 修复ios上微信唤醒app崩溃的问题
 * Android端重构

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: 4.2.0
+version: 4.2.1
 homepage: https://github.com/OpenFlutter/fluwx
 
 environment: