fix f string inconsistencies

Author: wesleyacheng

beginner_source/basics/buildmodel_tutorial.py

@@ -37,8 +37,8 @@
 # `torch.cuda <https://pytorch.org/docs/stable/notes/cuda.html>`_ is available, else we
 # continue to use the CPU.
 
-device = 'cuda' if torch.cuda.is_available() else 'cpu'
-print('Using {} device'.format(device))
+device = "cuda" if torch.cuda.is_available() else "cpu"
+print(f"Using {device} device")
 
 ##############################################
 # Define the Class

beginner_source/basics/quickstart_tutorial.py

@@ -89,7 +89,7 @@
 
 # Get cpu or gpu device for training.
 device = "cuda" if torch.cuda.is_available() else "cpu"
-print("Using {} device".format(device))
+print(f"Using {device} device")
 
 # Define model
 class NeuralNetwork(nn.Module):