Solve issue of expired token (unitxt-assistance).

The litellm.embaded used to faild since it handles the createion of authentication
token using apikey, but it doesn't hadle the token time expiering. By reinit
the package, litellm will create new token.

src/unitxt/assistant/app.py

@@ -1,4 +1,5 @@
 import datetime
+import importlib
 import json
 import os
 import uuid
@@ -22,6 +23,7 @@ def load_data():
 
 def search(query, metadata_df, embeddings, max_tokens=5000, min_text_length=50):
     # Generate embedding for the query using litellm
+    importlib.reload(litellm)  # Reload the litellm module to clear any cached state
     response = litellm.embedding(
         model="watsonx/intfloat/multilingual-e5-large",
         input=[query],