add changelog date (#74)

Author: johannes-vogel

CHANGELOG.md

@@ -5,9 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## Version 0.5.0 - tbd
-
-### Added
+## Version 0.5.0 - 2023-05-03
 
 ### Changed
 
@@ -22,8 +20,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Aligned `cds.Request` instantiation with other protocols for more consistent usage in custom handlers
 
-### Removed
-
 ## Version 0.4.1 - 2023-03-29
 
 ### Fixed