Fix zha test RuntimeWarning (#99519)

tests/components/zha/test_config_flow.py

@@ -10,6 +10,7 @@ import serial.tools.list_ports
 from zigpy.backups import BackupManager
 import zigpy.config
 from zigpy.config import CONF_DEVICE, CONF_DEVICE_PATH
+import zigpy.device
 from zigpy.exceptions import NetworkNotFormed
 import zigpy.types
 
@@ -1181,6 +1182,7 @@ async def test_onboarding_auto_formation_new_hardware(
 ) -> None:
     """Test auto network formation with new hardware during onboarding."""
     mock_app.load_network_info = AsyncMock(side_effect=NetworkNotFormed())
+    mock_app.get_device = MagicMock(return_value=MagicMock(spec=zigpy.device.Device))
     discovery_info = usb.UsbServiceInfo(
         device="/dev/ttyZIGBEE",
         pid="AAAA",