Fails to detect Pipewire without environment variables.

[vi]

cpal::platform::available_hosts() does not list pipewire even if /run/pipewire/pipewire-0 is available.

Workaround: PIPEWIRE_RUNTIME_DIR=/run/pipewire.

Other tools like pw-cli use /run/pipewire/pipewire-0 as a fallback socket path, so CPAL should probably do that as well.

[roderickvd]

Should be fixed by #1371.