Field not found: Roles

```text
$ go run ./examples/scanner
panic: failed to enable BLE stack: MapToStruct: Field not found: Roles

goroutine 1 [running]:
main.must(...)
	/dev/shm/bluetooth/examples/scanner/main.go:23
main.main()
	/dev/shm/bluetooth/examples/scanner/main.go:11 +0x1df
```

os: Archlinux
kernel: 5.8.10
bluez: 5.55
go:  1.15.2