[Podman] How to run a user systemd service in a GitHub Actions workflow

Here is a mini demo of how to run a web server (nginx) with podman in a user systemd service with Github Actions: https://github.com/eriksjolund/user-systemd-service-actions-workflow I noticed two non obvious things: 1. A short sleep was needed after loginctl enable-linger runner 2. systemctl needs to be run with the environment variable XDG_RUNTIME_DIR=/run/user/$UID