Fix deprecated Django API

Signed-off-by: Yassine Ilmi <9211413+yilmi@users.noreply.github.com>

Author: yilmi

vulnerabilities/models.py

@@ -25,7 +25,7 @@
 
 from django.db import models
 from django.core.exceptions import ValidationError
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 from packageurl.contrib.django.models import PackageURLMixin
 from packageurl import PackageURL