chore(agent-policy): prepare generation 21 - #101

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: oras-project/setup-oras@22ce207df3b08e061f537244349aac6ae1d214f6. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/