Add Models#delete to the changelog

Author: alexrudall

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add Responses endpoints - thanks to my excellent colleague [@simonx1](https://github.com/simonx1) for your work on this!
 - Add docs for the Deepseek chat API.
+- Add Models#delete - thanks to [bennysghost](https://github.com/bennysghost).
 
 ### Fixed