Running without `--privileged` returns a mount error

```console
$ sudo podman run --rm ghcr.io/osbuild/image-builder-cli
mount: /run/osbuild: permission denied.
       dmesg(1) may have more information after failed mount system call.
```

I expect the container:

- not to require `--privileged` for showing help
- privileged commands (`build`) to show a helpful error