Drop asynctest (#44746)

tests/components/config/test_customize.py

@@ -1,12 +1,11 @@
 """Test Customize config panel."""
 import json
+from unittest.mock import patch
 
 from homeassistant.bootstrap import async_setup_component
 from homeassistant.components import config
 from homeassistant.config import DATA_CUSTOMIZE
 
-from tests.async_mock import patch
-
 
 async def test_get_entity(hass, hass_client):
     """Test getting entity."""