fix error

app.py

@@ -12,6 +12,7 @@ from keras import backend as K
 import pandas as pd
 from transformers import TFAutoModel, AutoTokenizer
 from sklearn.model_selection import train_test_split
+import json
 
 # load the tokenizer and transformer model
 tokenizer = AutoTokenizer.from_pretrained("xlm-roberta-base",max_length=60) #xlm-roberta-base bert-base-multilingual-cased