Replace pytest.mark.skip with pytest.mark.xfail(strict=True)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/components/google_generative_ai_conversation/test_init.py

@@ -1309,6 +1309,10 @@ async def test_migration_from_v2_1(
     }
 
 
+@pytest.mark.xfail(
+    reason="Flaky due to Python 3.14.3 asyncio changes - see home-assistant/core#162263",
+    strict=True,
+)
 async def test_devices(
     hass: HomeAssistant,
     mock_config_entry: MockConfigEntry,