debug backend API for TAB 'search' (#2389)

### What problem does this PR solve?
#2247

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

rag/llm/embedding_model.py

@@ -15,7 +15,7 @@
 #
 import re
 from typing import Optional
-import  threading
+import threading
 import requests
 from huggingface_hub import snapshot_download
 from openai.lib.azure import AzureOpenAI