Fix Python style issue: remove unused typing.cast import

- Remove unused `typing.cast` import from test_clickzetta.py
- This resolves the Python Style CI check failure

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

api/tests/integration_tests/vdb/clickzetta/test_clickzetta.py

@@ -1,5 +1,4 @@
 import os
-from typing import cast
 
 import pytest