refactor: remove unused imports.

common/djangoapps/student/models.py

@@ -24,7 +24,6 @@ from importlib import import_module
 from urllib.parse import urlencode
 import warnings
 
-import six
 from config_models.models import ConfigurationModel
 from django.apps import apps
 from django.conf import settings
@@ -53,7 +52,6 @@ from opaque_keys.edx.django.models import CourseKeyField, LearningContextKeyFiel
 from opaque_keys.edx.keys import CourseKey
 from pytz import UTC, timezone
 from simple_history.models import HistoricalRecords
-from six import text_type
 from slumber.exceptions import HttpClientError, HttpServerError
 from user_util import user_util
 

common/djangoapps/student/roles.py

@@ -8,7 +8,6 @@ import logging
 from abc import ABCMeta, abstractmethod
 from collections import defaultdict
 
-import six
 from django.contrib.auth.models import User  # lint-amnesty, pylint: disable=imported-auth-user
 from opaque_keys.edx.django.models import CourseKeyField