bug#68512: Qutebrowser 3, no sound from pipewire-only system

[chris]

This attempt from the discussion here 
https://lists.gnu.org/archive/html/guix-devel/2021-03/msg00441.html
```
(define s (open-connection))

(display (derivation->output-path
          (package-derivation s pipewire #:graft? #f) "out"))
```

It runs but returns the wrong store path,
/gnu/store/kqw8zs84px1vzw98yv9xax4rc0n612qy-pipewire-0.3.77

The $(guix build pipewire) command returns this,
/gnu/store/8572wxb5138hanhvn1lbfdm1kicxsd2k-pipewire-1.0.0

Thanks,

Chris