Use from __future__ import annotations in tests

To ensure that we work with deferred types.

Author: bdowning

tests/test_asyncpg.py

@@ -1,3 +1,7 @@
+# ruff: noqa: UP007
+
+from __future__ import annotations
+
 import asyncio
 import json
 import os

tests/test_dataclasses.py

@@ -1,3 +1,7 @@
+# ruff: noqa: UP007
+
+from __future__ import annotations
+
 import uuid
 from dataclasses import dataclass
 from typing import Annotated, Optional