Support netbox 3.2.x versions

[tsv1991]

When I upgrade Netbox to version 3.2.0, netbox_ddns plugin can not been installed.

Traceback (most recent call last):
  File "/opt/netbox-3.2.0/netbox/manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/django/core/management/__init__.py", line 446, in execute_from_command_line
    utility.execute()
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/django/core/management/__init__.py", line 420, in execute
    django.setup()
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/django/apps/registry.py", line 124, in populate
    app_config.ready()
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/netbox_ddns/__init__.py", line 25, in ready
    super().ready()
  File "/opt/netbox-3.2.0/netbox/extras/plugins/__init__.py", line 68, in ready
    template_extensions = import_object(f"{self.__module__}.{self.template_extensions}")
  File "/opt/netbox-3.2.0/netbox/extras/plugins/utils.py", line 31, in import_object
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/netbox_ddns/template_content.py", line 5, in <module>
    from . import tables
  File "/opt/netbox-3.2.0/venv/lib64/python3.9/site-packages/netbox_ddns/tables.py", line 4, in <module>
    from utilities.tables import BaseTable, ToggleColumn
ImportError: cannot import name 'BaseTable' from 'utilities.tables' (/opt/netbox-3.2.0/netbox/utilities/tables.py)```

[tsv1991]

#25 I prepared this PR for fast upgrade to NetBox 3.2.0, but it breaks working with lower versions.

[tsv1991]

I modified PR #25 with support NetBox 3.1.x and 3.2.x.

Now fully tested on NetBox 3.1.7, 3.1.8, 3.1.10 and 3.2.0

[YWatchman]

Merged #25