saml: convert querysets to proper lists (#42656)

src/authentic2/saml/models.py

@@ -25,6 +25,7 @@ from authentic2.utils import normalize_attribute_values
 
 from django.db import models
 from django.db.models import Q
+from django.db.models.query import QuerySet
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.utils import six
@@ -335,6 +336,8 @@ class SAMLAttribute(models.Model):
         name = self.name
         friendly_name = self.friendly_name or None
         values = ctx.get(self.attribute_name)
+        if isinstance(values, QuerySet):
+            values = list(values)
         if not isinstance(values, (list, tuple, set)):
             values = [values]
         for value in values: