Adds support to Django 3.0

[pyMan]

I'm getting this error:

Traceback (most recent call last):
  File "C:\Users\xxxxx\.virtualenvs\yyyyy\lib\site-packages\django\db\utils.py", line 111, in load_backend
    return import_module('%s.base' % backend_name)
  File "C:\Python38\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "C:\Users\xxxxx\.virtualenvs\yyyyy\lib\site-packages\sql_server\pyodbc\base.py", line 42, in <module>
    from .operations import DatabaseOperations
  File "C:\Users\xxxxx\.virtualenvs\yyyyy\lib\site-packages\sql_server\pyodbc\operations.py", line 12, in <module>
    from django.utils.six import string_types
ModuleNotFoundError: No module named 'django.utils.six'

django.utils.six doesn't exist anymore in django 3.

[hingston]

This project is abandoned. It has been forked and is maintained here now: https://github.com/ESSolutions/django-mssql-backend/issues/18