fix: ruff findings

tests/test_hour_classification.py

@@ -11,11 +11,10 @@ Four splits sum to exactly 3600s. Disabled time is never an hour state.
 import sys
 from pathlib import Path
 
-import pytest
 
 sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
 
-from fenris.hour_classify import classify_hour, HourSplit, ACTIVE_THRESHOLD_BYTES
+from fenris.hour_classify import classify_hour, ACTIVE_THRESHOLD_BYTES
 
 HOUR_SECONDS = 3600