chore: update Python version to 3.9 and add future annotations for type hints

Author: twangodev

.github/workflows/python.yml

@@ -72,7 +72,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.x"
+          python-version: "3.9"
 
       - name: Install uv
         uses: astral-sh/setup-uv@v4

tests/integration/conftest.py

@@ -1,5 +1,7 @@
 """Fixtures for integration tests."""
 
+from __future__ import annotations
+
 import os
 from pathlib import Path