Update app.py

app.py

@@ -34,7 +34,7 @@ from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 from markdownify import markdownify
 import chargebee
-import pyrebase
+import pyrebase4 as pyrebase
 import streamlit.components.v1 as components
 import time
 import warnings