chore: use if TYPE_CHECKING: blocks (#2866)

unit_test/audit_test.py

@@ -1,4 +1,5 @@
-import contextlib
+from __future__ import annotations
+
 import subprocess
 from pathlib import Path
 from unittest.mock import Mock, patch
@@ -8,6 +9,10 @@ import pytest
 from cibuildwheel import errors
 from cibuildwheel.audit import needs_audit, run_audit
 
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    import contextlib
+
 
 def mock_virtualenv() -> contextlib.AbstractContextManager[Mock]:
     return patch(