fix windows label bug

examples/image_classification/imagenet_dataset.py

@@ -50,7 +50,7 @@ class ImageNetDataset(DatasetFolder):
     def __getitem__(self, idx):
         img_path, label = self.samples[idx]
         img = cv2.imread(img_path).astype(np.float32)
-        label = np.array([label])
+        label = np.array([label]).astype(np.int64)
         return self.transform(img), label
 
     def __len__(self):