fix: remove unused DbVersionError import from cli/__init__

The import was a leftover from the check_migrations design (issuecomment-2903):
DbVersionError is defined in db_store but migrate() never raises it, so the
import was dead. Pyright flagged it as reportUnusedImport.

bot_bottle/cli/__init__.py

@@ -8,7 +8,6 @@ from __future__ import annotations
 import sys
 
 from ..audit_store import AuditStore
-from ..db_store import DbVersionError
 from ..log import Die, die, error
 from ..manifest import ManifestError
 from ..queue_store import QueueStore