bump to 4.4.6

CHANGELOG.md

+# 4.4.6
+* Response里asString更名为asRecord.
+
 # 4.4.5
 * Response相关实体类增加asString方法，以方便debug.
 

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: 4.4.5
+version: 4.4.6
 homepage: https://github.com/OpenFlutter/fluwx
 
 environment: