Replace ugettext_lazy with gettext_lazy

[sumanthratna]

when running python3 -Wd manage.py runserver in my Django 3.0 project, I see:

venv/lib/python3.8/site-packages/dbbackup/apps.py:12: RemovedInDjango40Warning: django.utils.translation.ugettext_lazy() is deprecated in favor of django.utils.translation.gettext_lazy().
  verbose_name = _('Backup and restore')
/venv/lib/python3.8/site-packages/dbbackup/apps.py:12: RemovedInDjango40Warning: django.utils.translation.ugettext_lazy() is deprecated in favor of django.utils.translation.gettext_lazy().
  verbose_name = _('Backup and restore')

I'm unsure of any unintended consequences, but gettext_lazy has been available since Django 1.8 or earlier

[jonathan-s]

Thank you for fixing this @sumanthratna, gettext_lazy is an alias for ugettext_lazy there should not be any issues with this.

[johnthagen]

@jonathan-s Would it be possible to get a new minor release with this fix published to PyPI? We run our tests with -Werror and this requires us to add some suppressions (We are running Django 3.1).