Prepare changelog for 0.4.0

Authored-by: Leonhardt Koepsell <[email protected]>

Author: lnhrdt

CHANGELOG.md

@@ -9,7 +9,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [0.4.0] - 2025-04-25
 
 ### Added