2to3: add package host tool

2to3: add package host tool

2to3 is a Python program that reads Python 2.x source code and applies a
  series of fixers to transform it into valid Python 3.x code. The standard
  library contains a rich set of fixers that will handle almost all code. 2to3
  supporting library lib2to3 is, however, a flexible and generic library, so it
  is possible to write your own fixers for 2to3. lib2to3 could also be adapted
  to custom applications in which Python code needs to be edited automatically.

This tool is necessary for fail2ban package because of issue
  https://github.com/openwrt/packages/issues/17311
  https://github.com/openwrt/packages/pull/17341

Simple 2to3.py script from Debian, thanks to Matthias Klose <doko@ubuntu.com>
From: https://salsa.debian.org/cpython-team/python3-defaults

Co-authored-by: Jeffery To <jeffery.to@gmail.com>
Signed-off-by: Kerma Gérald <gandalf@gk2.net>