change defeault pytorch device to cpu

app.py

@@ -7,6 +7,7 @@ __all__ = ['path', 'files', 'dls', 'learn', 'categories', 'label_func', 'image_c
 from fastai.vision.all import ImageDataLoaders, URLs, untar_data, get_image_files, Resize, \
     vision_learner, resnet34, error_rate, default_device, load_learner, show_image, PILImage
 import torch
+torch.set_default_device('cpu')
 
 # %% cat_classifier.ipynb 3
 path = untar_data(URLs.PETS)