Update requirements.txt with specific package versions

- Upgrade LangChain and related packages to latest stable versions
- Add Transformers, PyTorch, Accelerate, and SafeTensors dependencies
- Remove HuggingFace-specific LangChain package
- Specify minimum version requirements for better compatibility

requirements.txt

@@ -2,8 +2,11 @@ fastapi
 uvicorn
 requests
 pydantic>=2.0.0
-langchain
-langchain-huggingface
-langchain-core
-langgraph > 0.2.27
-python-dotenv
+langchain>=0.1.0
+langchain-core>=0.1.10
+langgraph>=0.2.27
+python-dotenv>=1.0.0
+transformers>=4.36.0
+torch>=2.0.0
+accelerate>=0.26.0
+safetensors>=0.4.0