Fix Langchain prompt module imports and update dependencies

main.py

@@ -11,8 +11,8 @@ from pydantic import BaseModel
 from dotenv import load_dotenv
 
 from langchain_openai import ChatOpenAI
-from langchain.prompts import ChatPromptTemplate, MessagesPlaceholder
-from langchain.schema import HumanMessage, AIMessage, SystemMessage
+from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
+from langchain_core.messages import HumanMessage, AIMessage, SystemMessage
 from langchain.memory import ConversationBufferWindowMemory
 from langchain_community.tools import DuckDuckGoSearchRun
 

requirements.txt

@@ -5,5 +5,7 @@ duckduckgo-search
 python-dotenv
 pydantic
 langchain
+langchain-core
 langchain-community
 python-multipart
+requests