1.0.4: Replace deprecated thread.is_alive and xml.getchildren methods

[MajorBreakfast]

• Fixes the is_alive issue. Based on @sh00t2kill's branch (I just picked on of the three PRs that are currently open about this)
• Also fixes the xml.getchildren issue. The method was removed in python 3.9

How to try it locally:

• pip3 install git+https://github.com/MajorBreakfast/ozmo
• ozmo login
• ozmo clean 10

[MajorBreakfast]

@Ligio Cool :) thx