Drop some Python 2 compatibility.

paste/models.py

@@ -3,7 +3,7 @@ from django.core.validators import MaxLengthValidator
 from django.utils import timezone
 from datetime import datetime, timedelta
 from webtools import settings
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import gettext_lazy as _
 import hashlib
 import uuid