Sierpinski-Graph Demo: TypeError: draw_graph() got an unexpected keyword argument 'show_weight'

In `notebooks/Sierpinski-Graph.ipynb`:
<img width="804" alt="showWeightError" src="https://user-images.githubusercontent.com/24109/141051330-91efdf6a-0485-4fdd-ab46-247eb54cf8ca.png">

Changing the argument name to `weights` fixes it. 



