Add RAG chatbot application

requirements.txt

@@ -1,6 +1,6 @@
-langchain==0.3.21
-langchain-community==0.3.20
-langchain-huggingface==0.1.2
+langchain>=0.1.0
+langchain-community>=0.0.10
+langchain-huggingface>=0.0.1
 sentence-transformers>=2.2.2
 faiss-cpu>=1.7.4
 pypdf>=3.15.1
@@ -8,6 +8,6 @@ gradio>=4.0.0
 python-dotenv>=1.0.0
 torch>=2.0.0
 transformers>=4.34.0
-langchain-openai==0.3.9
+langchain-openai>=0.0.2
 openai>=1.0.0
 docling>=0.1.3