Update app.py

app.py

@@ -1,6 +1,10 @@
 import os
 import gradio as gr
-from os.environ.get("var2") import ChatBot
+import importlib
+var2 = os.environ.get("var2")
+if var2:
+    chatbot_module = importlib.import_module(module_name)
+    ChatBot = getattr(chatbot_module, "ChatBot")
 
 def main(user):
     if "/web" in user: