Tutorial2 issue

[ZvonimirBandic]

In tutorial 2, in code Tutorial2_spirals.py the line 22:

tf.set_random_seed(seed)

causes Attribution error (i.e. AttributeError: module 'tensorflow' has no attribute 'set_random_seed').

Should be replace with:

tf.random.set_seed(seed)

Not sure if this is worth a pull request, I think it is better to add it in issues so future users can find it. If you want me to create a PR let me know.