docs: add CHANGELOG entry for softprops/action-gh-release v3 bump (#47)

Backfills the entry for #45, which moved the release workflow to the
Node 24 runtime. No consumer-visible change (release.yml only runs on
tag push from this repo).

Author: anneschuth

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+- Bump `softprops/action-gh-release` from v2 to v3 in release workflow (moves release job to Node 24 runtime)
+
 ## [4.0.3] - 2026-04-21
 
 ### Changed