docs(changelog): 📝 update changelog for release

Author: MerleLiuKun

CHANGELOG.md

@@ -2,11 +2,12 @@
 
 All notable changes to this project will be documented in this file.
 
-## Version 0.9.0 (in development)
+## Version 0.9.0 (2022-12-26)
 
 ### What's New
 
 - Introduce new `Client` to operate YouTube DATA API. [#120](https://github.com/sns-sdks/python-youtube/issues/120).
+- More example to show library usage.
 
 ## Version 0.8.3 (2022-10-17)