Compatibility with Django 2.2.13

[Regis111]

$ pip show Django
Name: Django
Version: 2.2.13
Summary: A high-level Python Web framework that encourages rapid development and clean, pragmatic design.
Home-page: https://www.djangoproject.com/
Author: Django Software Foundation
Author-email: foundation@djangoproject.com
License: BSD
Location: /home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages
Requires: sqlparse, pytz
Required-by: django-taggit, django-picklefield, django-localflavor, django-leaflet, django-extra-views, django-embed-video, django-debug-toolbar, django-appconf

$ python --version
Python 3.7.6

I tried to setup package like instructions in read.me. After pip install django-cities-teryt I added cities_teryt to INSTALLED_APPS and then tried ./manage.py syncdb which resulted in such exception:

The .env file has been loaded...
Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/django/core/management/__init__.py", line 357, in execute
    django.setup()
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/django/apps/registry.py", line 114, in populate
    app_config.import_models()
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/django/apps/config.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/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 "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/cities_teryt/models.py", line 59, in <module>
    class County(Base):
  File "/home/regis/.local/share/virtualenvs/er-portal-_B-9ZmAC/lib/python3.7/site-packages/cities_teryt/models.py", line 63, in County
    province = models.ForeignKey(Province, verbose_name=_('Province'))
TypeError: __init__() missing 1 required positional argument: 'on_delete'

Could you tell me what am I doing wrong? Thank you.