Fix snapcast test warning (#116687)

tests/components/snapcast/conftest.py

@@ -1,7 +1,7 @@
 """Test the snapcast config flow."""
 
 from collections.abc import Generator
-from unittest.mock import AsyncMock, patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
@@ -20,5 +20,6 @@ def mock_create_server() -> Generator[AsyncMock, None, None]:
     """Create mock snapcast connection."""
     mock_connection = AsyncMock()
     mock_connection.start = AsyncMock(return_value=None)
+    mock_connection.stop = MagicMock()
     with patch("snapcast.control.create_server", return_value=mock_connection):
         yield mock_connection