style(db): use collections.abc for AsyncGenerator

Use collections.abc.AsyncGenerator instead of typing.AsyncGenerator
for modern Python 3.9+ compatibility. Auto-fixed by ruff linter.

Author: Sakeeb91

db/connection.py

@@ -5,8 +5,9 @@
 async support for multiple database backends.
 """
 
+from collections.abc import AsyncGenerator
 from contextlib import asynccontextmanager
-from typing import Any, AsyncGenerator
+from typing import Any
 
 from sqlalchemy import text
 from sqlalchemy.ext.asyncio import (