Fixed new pylint warnings.

use generator in any/all()
disable not-callable warnings
disable no-member warnings
Suppressed smaller pylint warnings
Pin edx-proctoring==3.5.0

lms/djangoapps/instructor/tests/test_services.py

@@ -5,8 +5,6 @@ import json
 from unittest import mock
 
 import pytest
-import mock
-import six
 from django.core.exceptions import ObjectDoesNotExist
 from opaque_keys import InvalidKeyError
 

lms/djangoapps/instructor/tests/test_tools.py

@@ -9,8 +9,6 @@ import unittest
 from unittest import mock
 
 import pytest
-import mock
-import six
 from django.contrib.auth.models import User  # lint-amnesty, pylint: disable=imported-auth-user
 from django.core.exceptions import MultipleObjectsReturned
 from django.test import TestCase