tests: fix warning about uncollectable TestApp (#53577)

tests/test_dashboard.py

@@ -11,7 +11,6 @@ from django.core.management import call_command
 from django.test import override_settings
 from django.urls import reverse
 from django.utils.six.moves.urllib import parse as urlparse
-from webtest import TestApp
 
 from combo.apps.dashboard.models import DashboardCell, Tile
 from combo.data.models import CellBase, ConfigJsonCell, Page, TextCell

tests/test_public.py

@@ -15,7 +15,6 @@ from django.urls import reverse
 from django.utils.http import quote
 from django.utils.six import StringIO
 from django.utils.six.moves.urllib import parse as urlparse
-from webtest import TestApp
 
 try:
     import mellon

tests/test_publik.py

@@ -5,7 +5,6 @@ import re
 import pytest
 from django.conf import settings
 from django.contrib.auth.models import Group, User
-from webtest import TestApp
 
 from combo.data.models import Page