fix(deps): update dependency @adobe/helix-html-pipeline to v6.29.12 - #2778

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: adobe-rnd/github-semantic-release-comment-action@main. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/