bump to 5.4.1

CHANGELOG.md

+# 5.4.1
+* Android替换过时方法toLowerCase()为lowercase()
+
 # 5.4.0
 * 增加鸿蒙分享网页和小程序，微信sdk升级1.0.6
 

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: 5.4.0
+version: 5.4.1
 homepage: https://github.com/OpenFlutter/fluwx
 
 environment: