Drop asynctest (#44746)

tests/components/blueprint/test_websocket_api.py

@@ -1,12 +1,11 @@
 """Test websocket API."""
 from pathlib import Path
+from unittest.mock import Mock, patch
 
 import pytest
 
 from homeassistant.setup import async_setup_component
 
-from tests.async_mock import Mock, patch
-
 
 @pytest.fixture(autouse=True)
 async def setup_bp(hass):