fix(v0.40.1): add `from __future__ import annotations` to quickstart.py for py3.9

Hotfix: `_pick_quickstart_model() -> tuple[str, str | None]` uses PEP 604
union syntax which Python 3.9 rejects at module-import time. Closes the CI
collection failure on the ubuntu-latest/3.9 matrix without changing behaviour.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

soup_cli/commands/quickstart.py

@@ -1,5 +1,7 @@
 """soup quickstart — one command for a complete demo (create data + config + train)."""
 
+from __future__ import annotations
+
 import json
 from pathlib import Path