setup.py version pinning not reflected in install instructions

[smangham]

setup.py contains the following dynamically-generated requirement:

[...]

if minor < 7:
    cp = str(30+minor)
else:
    cp = '38'

if dist_name == 'ubuntu':
   dist_ver = int(dist_ver.split('.')[0])
if dist_ver >= 14:
    dist =  'ubuntu-14.04'
if dist_ver >= 16:
    dist = 'ubuntu-16.04'
if dist_ver >= 18:
    dist = 'ubuntu-18.04'
if dist_ver >= 20:
    dist = 'ubuntu-20.04'
[....]

wxpython_url = 'wxPython @ https://extras.wxpython.org/wxPython4/extras/linux/gtk3/'+dist+'/wxPython-4.1.0-cp'+cp+'-cp'+cp+'-linux_x86_64.whl'

This forces Python 3.8 and wxPython 4.1.0. As a result, it's not possible to install with Python 3.10. Even on 3.8, the section in the install guide:

python3 -m pip install -U -f https://extras.wxpython.org/wxPython4/extras/linux/gtk3/ubuntu-22.04 wxPython

Is also wrong, as it still installs 4.2.1, which is incompatible. The Python and wxPython version pins should be made explicit in the setup.py.

Whilst it forces the ubuntu-20.04 version of wxPython, this also seems to work on Ubuntu 22.04 - but that pin should ideally be removed.