[TASK] Prepare release of version 8.9.0 (#1327)

Part of #1326

Author: oliverklee

CHANGELOG.md

@@ -7,6 +7,18 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ### Added
 
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+## 8.9.0: New features, bug fixes and deprecations
+
+### Added
+
 - `RuleSet::removeMatchingRules()` method
   (for the implementing classes `AtRuleSet` and `DeclarationBlock`) (#1249)
 - `RuleSet::removeAllRules()` method
@@ -51,8 +63,6 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 - Providing zero as the line number argument to `Rule::setPosition()` is
   deprecated (pass `null` instead if there is no line number) (#1225, #1233)
 
-### Removed
-
 ### Fixed
 
 - Set line number when `RuleSet::addRule()` called with only column number set