docs: update changelogs for 6.0.0-rc.5 release

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: lcharette

CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+## [6.0.0-rc.5] - 2026-06-03
+
 ### Changed
 - Bump minimum Node.js requirement from 18 to 20 (Vitest 4 requires `^20 || ^22 || >=24`).
 - Bump `@vitest/coverage-v8` from `^3.1.1` to `^4.1.0` to match Vitest 4.