fix(nextcms-14723): pin the PR title check to ubuntu-24.04, replacing an invalid runner label - #2

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: ytanikin/pr-conventional-commits@1.4.1. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/