Refactor test_session_memory.py to simplify imports

- Removed unused imports and streamlined the import statements for clarity and maintainability.
- This change enhances the readability of the test file by focusing on the necessary components.

tests/test_session_memory.py

@@ -2,12 +2,10 @@
 
 import pytest
 import tempfile
-import os
 from pathlib import Path
 import asyncio
 
-from agents import Agent, Runner, RunConfig, SQLiteSessionMemory
-from agents.memory import SessionMemory
+from agents import Agent, Runner, SQLiteSessionMemory
 
 from .fake_model import FakeModel
 from .test_responses import get_text_message