docs: update changelog for v0.4.0

Author: luisaveiro

CHANGELOG.md

@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [v0.4.0] - 2023-12-30
+### Added
+- `retry` and `withUrl` methods.
+
+### Removed
+- `PendingRequestUrl` instance within the HTTP Client.
+
 ## [v0.3.0] - 2023-12-29
 ### Added
 - `withOption` and `withOptions` helper methods.