Django 3 incompatibility

Fails to build with django 3:

Traceback (most recent call last):
  File "./manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/local/lib/python3.7/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/usr/local/lib/python3.7/site-packages/django/core/management/__init__.py", line 377, in execute
    django.setup()
  File "/usr/local/lib/python3.7/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/usr/local/lib/python3.7/site-packages/django/apps/registry.py", line 114, in populate
    app_config.import_models()
  File "/usr/local/lib/python3.7/site-packages/django/apps/config.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/local/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/usr/local/lib/python3.7/site-packages/automationcommon/models.py", line 21, in <module>
    class Creatable(models.Model):
  File "/usr/local/lib/python3.7/site-packages/automationcommon/models.py", line 28, in Creatable
    if StrictVersion(django.get_version()) >= StrictVersion('2.0') else \
  File "/usr/local/lib/python3.7/site-packages/django/db/models/fields/related.py", line 801, in __init__
    raise TypeError('on_delete must be callable.')
TypeError: on_delete must be callable.

automationcommon requires django<2.3,>=1.11

limit django v2.2 until ready for v3