Migre l'association conférencier<->session de Ting vers Doctrine - #2387

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: AndreKurait/docker-cache@0.6.0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/