Update autograd_tutorial.py, added whitespace #2802 (#2815)

* Update formatting in the autograd_tutorial.py 

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Co-authored-by: Svetlana Karslioglu <svekars@meta.com>

Author: Satyamkhadka

beginner_source/blitz/autograd_tutorial.py

@@ -266,7 +266,7 @@
 z = torch.rand((5, 5), requires_grad=True)
 
 a = x + y
-print(f"Does `a` require gradients? : {a.requires_grad}")
+print(f"Does `a` require gradients?: {a.requires_grad}")
 b = x + z
 print(f"Does `b` require gradients?: {b.requires_grad}")