Update app.py

app.py

@@ -9,8 +9,8 @@ from langchain.chains import ConversationalRetrievalChain
 from langchain.memory import ConversationBufferMemory
 from langchain_openai import ChatOpenAI
 from langchain_experimental.text_splitter import SemanticChunker
-
-openai_api_key = "YOUR_OPENAI_API_KEY_HERE"
+import os
+openai_api_key = os.getenv("OPENAI_API_KEY")
 
 vectorstore = None
 llm = None