chore: update CHANGELOG for v0.4.2 and version bump to 0.4.2

- Added support for Azure OpenAI and built-in Volcengine Ark provider.
- Introduced GPT 5.5 model.
- Enhanced retry logic for HTTP status codes.

CHANGELOG.md

@@ -1,3 +1,13 @@
+# v0.4.2 (2026-04-24)
+
+## Features
+- Add Azure OpenAI provider support
+- Add built-in Volcengine Ark provider support (#741)
+- Add GPT 5.5 model
+
+## Fixes
+- Enhance retry logic and configuration for HTTP status codes
+
 # v0.4.1 (2026-04-23)
 
 ## Features