Python 3.9, 3.10 support (install fails with `vatnumber`)

[banagale]

I've tried installing django-plans using python 3.9 and 3.10 using:

pip install -e git://github.com/cypreess/django-plans.git#egg=django-plans

The install fails at vatnumber, it looks like this library is no longer maintained.

I wonder if pyvat would be a good drop-in replacement.

Collecting vatnumber>=1.2
  Using cached vatnumber-1.2.tar.gz (19 kB)
  Preparing metadata (setup.py) ... error
  ERROR: Command errored out with exit status 1:
   command: /Users/x/.virtualenvs/dj-plans-example39/bin/python3.9 -c 'import io, os, sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/51/z2bf1rq1007gxp1c2s6qvzym0000gn/T/pip-install-qp14ffg7/vatnumber_2dd164258b0242fdb0ad022a174a5bd3/setup.py'"'"'; __file__='"'"'/private/var/folders/51/z2bf1rq1007gxp1c2s6qvzym0000gn/T/pip-install-qp14ffg7/vatnumber_2dd164258b0242fdb0ad022a174a5bd3/setup.py'"'"';f = getattr(tokenize, '"'"'open'"'"', open)(__file__) if os.path.exists(__file__) else io.StringIO('"'"'from setuptools import setup; setup()'"'"');code = f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /private/var/folders/51/z2bf1rq1007gxp1c2s6qvzym0000gn/T/pip-pip-egg-info-tv_x0e3n
       cwd: /private/var/folders/51/z2bf1rq1007gxp1c2s6qvzym0000gn/T/pip-install-qp14ffg7/vatnumber_2dd164258b0242fdb0ad022a174a5bd3/
  Complete output (1 lines):
  error in vatnumber setup command: use_2to3 is invalid.

[banagale]

It seems like maybe this was an issue due to trying to install the example project first.

[PetrDlouhy]

I just bumped into this issue. The problem isn't with python version, but rather with setuptools version. It works fine with setuptools until version 57. If testing this issue, it is needed to run pip with command pip install vatnumber --no-cache-dir to avoid reusing already compiled wheel, which would not show the issue.

[PetrDlouhy]

I realized, that python-stdnum would be better replacement for vatnumber. It is solved in #154