bump to 5.2.1

CHANGELOG.md

+# 5.2.1
+* Merge #658
+
 # 5.2.0
 * 为iOS分享小程序增加hdImageData选项
 * 优化Android图片分享逻辑，优先把LocalImagePath以最大限度保证图片质量

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: 5.2.0
+version: 5.2.1
 homepage: https://github.com/OpenFlutter/fluwx
 
 environment: