Python3.9 WIP

[wardi]

this is closer, but python environment is broken with

Traceback (most recent call last):
  File "/srv/app/ckan/registry/wsgi.py", line 8, in <module>
    from ckan.config.middleware import make_app
  File "/srv/app/ckan/registry/src/ckan/ckan/config/middleware/__init__.py", line 7, in <module>
    import six
  File "/srv/app/ckan/registry/lib/python3.9/site-packages/six.py", line 649, in <module>
    import struct
  File "/usr/lib/python3.9/struct.py", line 13, in <module>
    from _struct import *
ModuleNotFoundError: No module named '_struct'