CHANGELOG: fix date of 0.9.1 release (#1467)

Author: ahayzen-kdab

CHANGELOG.md

@@ -17,7 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/KDAB/cxx-qt/compare/v0.9.1...HEAD)
 
-## [0.9.1](https://github.com/KDAB/cxx-qt/compare/v0.9.0...v0.9.1) - 2026-08-03
+## [0.9.1](https://github.com/KDAB/cxx-qt/compare/v0.9.0...v0.9.1) - 2026-07-03
 
 ### Fixed