Update requirements.txt

requirements.txt

@@ -1,6 +1,5 @@
-gradio
-python-dotenv
-llama-index
-llama-index-embeddings-huggingface
-llama-index-llms-huggingface
-huggingface_hub==0.16.4
+gradio==3.31.1
+langchain==0.0.301
+huggingface_hub==0.15.1
+llama-index==0.5.6
+python-dotenv==1.0.0