fix: ruff findings

src/fenris/derive.py

@@ -12,7 +12,7 @@ No proportional allocation, endpoint assignment, or double counting.
 """
 import sqlite3
 from datetime import datetime, timedelta, timezone
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional
 
 from .hour_classify import classify_hour, HourSplit