chore: fix ruff UP035 in watcher

Made-with: Cursor

Author: Sayeem3051

ctxeng/watcher.py

@@ -4,9 +4,9 @@
 
 import threading
 import time
+from collections.abc import Callable
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Callable
 
 from ctxeng.models import Context