docs: add changelog entry for PR #374 (pre-commit autoupdate)

Agent-Logs-Url: https://github.com/tpvasconcelos/ridgeplot/sessions/7f739030-a077-4f38-9fca-09f0bf76a9bf

Co-authored-by: tpvasconcelos <17701527+tpvasconcelos@users.noreply.github.com>

Author: Copilot

docs/reference/changelog.md

@@ -5,7 +5,9 @@ This document outlines the list of changes to ridgeplot between each release. Fo
 Unreleased changes
 ------------------
 
-- ...
+### CI/CD
+
+- pre-commit autoupdate ({gh-pr}`374`)
 
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