OXDEV-8213: Change upcoming changelog version for new feature

Author: MarcelOxid

CHANGELOG-v9.md

@@ -4,7 +4,7 @@ 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).
 
-## [9.0.0] - 2024-07-04
+## [9.1.0] - Unreleased
 
 ### Added
 - `DataType\Filter\AbstractNumberFilter`