Can't use spice-app on macOS because GIO can't find handler for spice+unix scheme
Description of problem:
```
qemu-system-aarch64: info: Launching display with URI: spice+unix:///tmp/.U96NU1/spice.sock
qemu-system-aarch64: warning: GLib-GIO: No default handler found for url scheme 'spice+unix'.
qemu-system-aarch64: warning: GLib-GIO: No default handler found for url scheme 'spice+unix'.
qemu-system-aarch64: Failed to launch spice+unix:///tmp/.U96NU1/spice.sock URI: Operation not supported
qemu-system-aarch64: You need a capable Spice client, such as virt-viewer 8.0
```

```
$ virt-viewer --version
virt-viewer version 11.0
```
Steps to reproduce:
1. Have virt-viewer in $PATH
2. Run command above
3. Observe error above
Additional information: