Fix some security vulnerabilities. (#2160)

### What problem does this PR solve?

Fix some security vulnerabilities

### Type of change

- [x] Performance Improvement

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>

api/apps/llm_app.py

@@ -22,7 +22,7 @@ from api.db.db_models import TenantLLM
 from api.utils.api_utils import get_json_result
 from rag.llm import EmbeddingModel, ChatModel, RerankModel, CvModel, TTSModel
 import requests
-import ast
+
 
 @manager.route('/factories', methods=['GET'])
 @login_required