fix: keep release checks importable on python 3.9

check_release_assets.py built a tuple[..., int | None] alias at import, a TypeError on the 3.9 floor tools.md states, and check_release.py imports it. A test reads every script for unions and match statements evaluated at runtime.

scripts/check_release_assets.py

@@ -22,6 +22,7 @@ import re
 import subprocess
 import sys
 from collections.abc import Iterable
+from typing import Optional, Tuple
 
 sys.path.insert(0, os.path.dirname(__file__))
 from common import composition_tier, load_database
@@ -32,7 +33,8 @@ from largefiles import (
     registered_paths,
 )
 
-Finding = tuple[str, str, int, int | None]
+# Evaluated at import, where `int | None` needs Python 3.10.
+Finding = Tuple[str, str, int, Optional[int]]
 
 
 def expected_assets(db: dict, gitignore_text: str) -> dict[str, int]: