fixed all test issues

tests/unit/test_database_models.py

@@ -5,7 +5,7 @@ operations. Uses an in-memory SQLite database for isolated testing.
 """
 from __future__ import annotations
 
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, timezone
 
 import pytest
 from sqlalchemy import create_engine, select
@@ -356,7 +356,7 @@ class TestUserSession:
     def test_session_is_expired(self, db_session: Session):
         """Test session expiration check."""
         # Create expired session
-        expired = datetime.utcnow() - timedelta(hours=1)
+        expired = datetime.now(timezone.utc) - timedelta(hours=1)
         session = UserSession(
             session_id="expired-session",
             token_hash="hash",