fix(updater): add 'from __future__ import annotations' for py3.9 compat

CI on 3.9 caught a real runtime error: 'str | Path | None' (PEP-604)
isn't valid in 3.9 outside of stringified annotations. Adding the
__future__ import makes all annotations lazy strings, fixing 3.9
without changing the type signatures.

Author: leeguooooo

src/claude_statusbar/updater.py

@@ -2,6 +2,7 @@
 """
 Auto-updater for claude-statusbar
 """
+from __future__ import annotations
 
 import json
 import logging