Why isn’t there any good hacking books written in Python 3

[Larz60+]

Python 2 is still very valid and will be until at least 2020

that's only a year and a half away, so be cautious
Also, if you are using python 2 you are missing out on some fantastic improvements.
You should be able to modify code for python 3 with a little effort. There's also a tool '2to3' that will do most if not all of the work for you, see: https://docs.python.org/2/library/2to3.html