ci: use podman gitlab-runner for multiarch builds

The build runs in two stages:

1. Cross compilation for target architecture on native arch image
2. Installation into target architecture image

It require actually a third stage to workaround an issue in podman/buildah: https://github.com/containers/buildah/issues/4742

Configuring a gitlab-runner with podman:

1. Follow this documentation: https://docs.gitlab.com/runner/executors/docker.html#use-podman-to-run-docker-commands
2. Install the crun and qemu-user-static packages