Update release date

Author: visr

docs/changelog.qmd

@@ -9,7 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Changed
 
-## [v2024.9.0] - 2024-06-18
+## [v2024.9.0] - 2024-06-20
 
 ### Added
 - Support for concentration state and time for Delwaq coupling.