Note #1978 in changelog

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Co-authored-by: Goooler <10363352+Goooler@users.noreply.github.com>

Author: Copilot

docs/changes/README.md

@@ -3,6 +3,9 @@
 
 ## [Unreleased](https://github.com/GradleUp/shadow/compare/9.4.0...HEAD) - 2026-xx-xx
 
+### Changed
+
+- Update Kotlin to 2.3.20. ([#1978](https://github.com/GradleUp/shadow/pull/1978))
 
 ## [9.4.0](https://github.com/GradleUp/shadow/releases/tag/9.4.0) - 2026-03-15