add missing connection in tests

tests/test_fastapi/test_relations_with_nested_defaults.py

@@ -73,6 +73,7 @@ def create_test_database():
 
 @pytest.fixture()
 async def sample_data():
+    async with database:
         country = await Country(id=1, name="USA").save()
         author = await Author(id=1, name="bug", rating=5, country=country).save()
         await Book(