Update app.py

app.py

@@ -441,7 +441,7 @@ def invoke (prompt, file, history, rag_option, model_option, openai_api_key, k=3
         #buffer = io.BytesIO()
         #image.save(buffer, format='PNG')
         #desiredObject = buffer.getbuffer()
-        b = BytesIO()  
+        b = io.BytesIO()  
         image.save(b, format='PNG')
         
         history[-1][1] =  "<img src='data:image/png;base64,{0}'/>".format(b64encode(b.getvalue()).decode('utf-8'))  #file.name,