Update Demo-Iris notebook

[mandjevant]

Demo-Iris:

• Update notebook to version 4.
• Remove skdata.iris.view in favour of sklearn.datasets.load_iris.
• Use pandas dataframe to better simulate a real-world application.
• Generator().next() has been renamed to Generator().__next__().
• Rewrote print statements to match Python3 format.

[bjkomer]

Thanks for the notebook update, looks good to me!