fix syntax error

Author: DylannCordel

djangosaml2/backends.py

@@ -217,7 +217,7 @@ def lookup_and_set_attribute(self, user, attr, attr_value_list) -> bool:
             if callable(user_attr):
                 return user_attr(attr_value_list)
             else:
-                return = set_attribute(user, attr, attr_value_list[0])
+                return set_attribute(user, attr, attr_value_list[0])
         else:
             logger.debug(f'Could not find attribute "{attr}" on user "{user}"')
         return False