test(config): import RetirementIssue in the xai migration fold regression

The rebase reconciled the import block against main's trimmed list and
dropped the one name the new test constructs, so the regression died with
a NameError before reaching apply_migration.

tests/hermes_cli/test_xai_retirement.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import yaml
 
 from hermes_cli.xai_retirement import (
+    RetirementIssue,
     _RETIRED_MODELS,
     _looks_like_xai,
     _normalize,