Fix importlib.metadata deprecation warning

[browniebroke]

Warning:

  django_countries/fields.py:21
    /home/runner/work/django-countries/django-countries/django_countries/fields.py:21: DeprecationWarning: SelectableGroups dict interface is deprecated. Use select.
      _entry_points = importlib.metadata.entry_points().get(

Fix #439

Note

I've used sys.version_info and changed the pre-existing check for version <3.8 to use the same approach. This way, pyupgrade should fix it automatically when the project drop the older Python versions.

[zyv]

Fixes https://github.com/SmileyChris/django-countries/issues/439 .

[browniebroke]

Fixes #439 .

Thanks, added to the description (to auto-close it)

[SmileyChris]

Fixed