Update train.py

Author: qnguyen3

train.py

@@ -141,4 +141,4 @@ def seed_everything(seed):
     # scheduler
     scheduler = StepLR(optimizer, step_size=7, gamma=configs['gamma'])
 
-    train(vision_transformer, train_loader, None, criterion, optimizer, scheduler)
+    train(vision_transformer, train_loader, valid_loader, criterion, optimizer, scheduler)