Drop Python 2. Support up to Python 3.11. Build wheels

[claudiodsf]

This PR makes the code compatible with Python <= 3.11.

The price for that is dropping Python 2, which I don't think is an issue anymore.

I also added a GitHub automation which uses cibuildwheel to build wheels for Linux, Mac and Windows. The automation will also publish packages to PyPi, as soon we make our first release 😉

The wheel build process is fairly long (1h 44m). You can check the results here: https://github.com/BackTrackBB/backtrackbb/actions/runs/5278332119 (All the produced wheels are in the "artifact" archive).

@npoiata, let me know if you can test this and how to proceed.