fix(api): ruff UP017 — use datetime.UTC alias in /api/downloads/stats

backend/app/api/downloads.py

@@ -5,7 +5,7 @@ status/source/artist. Returns slim records.
 Detail view: full DownloadEvent including the metadata JSONB.
 """
 
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 from quart import Blueprint, jsonify, request
 from sqlalchemy import func, select
@@ -112,7 +112,7 @@ async def downloads_stats():
     if window_hours < 1 or window_hours > 24 * 365:
         return jsonify({"error": "invalid_window_hours"}), 400
 
-    since = datetime.now(timezone.utc) - timedelta(hours=window_hours)
+    since = datetime.now(UTC) - timedelta(hours=window_hours)
     out = {"pending": 0, "running": 0, "ok": 0, "error": 0, "skipped": 0}
     async with get_session() as session:
         stmt = (