CI: Node 16 is deprecated

> Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/setup-python@v4. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

Possible solution: [setup-python@v5](https://github.com/actions/setup-python/releases/tag/v5)