change model test files

Author: Liyulingyue

graph_net/test/vision_model_test.py

@@ -1,10 +1,9 @@
 import argparse
 import os
-import json
+
 import torch
 import torchvision
 from torchvision import transforms
-import os
 import graph_net
 
 if __name__ == "__main__":