Fix weight initialization on neural_style_tutorial (#2673)

Co-authored-by: Nicolas Hug <contact@nicolas-hug.com>

advanced_source/neural_style_tutorial.py

@@ -56,7 +56,7 @@
 import matplotlib.pyplot as plt
 
 import torchvision.transforms as transforms
-import torchvision.models as models
+from torchvision.models import vgg19, VGG19_Weights
 
 import copy
 
@@ -262,7 +262,7 @@ def forward(self, input):
 # network to evaluation mode using ``.eval()``.
 # 
 
-cnn = models.vgg19(pretrained=True).features.eval()
+cnn = vgg19(weights=VGG19_Weights.DEFAULT).features.eval()