Add python3 support

[zorun]

We should definitely support python3 at this point...

[athompso]

Indeed - it's turning out be more-or-less impossible to install on CentOS/Rocky/Alma/RHEL 8.x without compiling a whole bunch of Python 2 modules from scratch.
Is anyone actively working on this?

[zorun]

I did some preliminary hacking around urllib2/requests here: https://github.com/zorun/bird-lg/tree/hacking

But there were still a lot of bytes/string issues crashing most endpoints.

I won't have time to work actively on this, so feel free to give it a spin!

[takenek]

https://github.com/zotanmew/bird-lg
here is a Python3 nice working version :-)