piston3 package is unnecessarily distro-specific (MAAS breaks after do-release-upgrade from focal to jammy)

Upgrading from MAAS 3.2 to 3.3 requires also upgrading from Focal to Jammy. The PPA for MAAS 3.2 only supports Focal and the PPA for MAAS 3.3 only supports Jammy.

After you upgrade from Focal to Jammy, MAAS is broken until you also upgrade it. This doesn't work (by default) in one step because there are 2 different PPAs.

The main reason it breaks is that the 3.2/focal python3-django-piston3 package incorectly places it's files in /usr/lib/python3.8 instead of /usr/lib/python3 and so can't be used by python3.11 on jammy.

This is simply due to a missing "--with python3" in debian/rules, which would allow the package to continue working for the brief period until the MAAS 3.3 upgrade is started because the files will be in the version-agnostic path (where they should be).

ModuleNotFoundError: No module named 'piston3'
Traceback (most recent call last):
  File "/usr/sbin/regiond", line 11, in <module>
    load_entry_point('maas==3.2.8', 'console_scripts', 'regiond')()
  File "/usr/lib/python3/dist-packages/maasserver/server.py", line 107, in run
    runMasterServices()
  File "/usr/lib/python3/dist-packages/maasserver/server.py", line 21, in runMasterServices
    runService("maas-regiond-master")
  File "/usr/lib/python3/dist-packages/provisioningserver/server.py", line 90, in runService
    UnixApplicationRunner(config).run()
  File "/usr/lib/python3/dist-packages/twisted/application/app.py", line 370, in run
    self.application = self.createOrGetApplication()
  File "/usr/lib/python3/dist-packages/twisted/application/app.py", line 432, in createOrGetApplication
    ser = plg.makeService(self.config.subOptions)
  File "/usr/lib/python3/dist-packages/maasserver/plugin.py", line 215, in makeService
    self._configureDjango()
  File "/usr/lib/python3/dist-packages/maasserver/plugin.py", line 86, in _configureDjango
    django.setup()
  File "/usr/lib/python3/dist-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/lib/python3/dist-packages/django/apps/registry.py", line 91, in populate
    app_config = AppConfig.create(entry)
  File "/usr/lib/python3/dist-packages/django/apps/config.py", line 224, in create
    import_module(entry)
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked