add "changed" labels

Author: matsev

CHANGES.md

@@ -10,6 +10,7 @@ This document is intended for Spotless developers.
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Changed
 * Use palantir-java-format 2.57.0 on Java 21. ([#2447](https://github.com/diffplug/spotless/pull/2447))
 
 ## [3.1.0] - 2025-02-20

plugin-gradle/CHANGES.md

@@ -3,6 +3,7 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `3.27.0`).
 
 ## [Unreleased]
+### Changed
 * Use palantir-java-format 2.57.0 on Java 21. ([#2447](https://github.com/diffplug/spotless/pull/2447))
 
 ## [7.0.2] - 2025-01-14

plugin-maven/CHANGES.md

@@ -3,6 +3,7 @@
 We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (starting after version `1.27.0`).
 
 ## [Unreleased]
+### Changed
 * Use palantir-java-format 2.57.0 on Java 21. ([#2447](https://github.com/diffplug/spotless/pull/2447))
 
 ## [2.44.3] - 2025-02-20