Update model field definitions to use gettext_lazy

[arthanson]

Proposed Changes

In order to correctly support internationalization, models need to be audited and add in the name as gettext_lazy string and update verbose_name where applicable to use gettext_lazy. See Django's use at https://github.com/django/django/blob/main/django/contrib/auth/models.py#L356

    slug = models.SlugField(
        _("slug"), <- add this
        max_length=100
    )

Justification

Model fields need their name (and where appropriate their verbose_name) as translatable strings.