should work now

app.py

@@ -8,7 +8,7 @@ def sign(input_img):
     input_img = Image.fromarray(input_img)
     prediction = sign_api.predict(input_img)
     print('prediction',prediction)
-    return prediction
+    return prediction['class']
 
 demo = gr.Interface(sign,inputs=gr.Image(shape=(200, 200)), outputs=gr.Label())
 demo.launch()