trivial: import reverse from django.urls

ckeditor/widgets.py

@@ -1,7 +1,7 @@
 from django import forms
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.core.serializers.json import DjangoJSONEncoder
 from django.template.loader import render_to_string
 from django.utils.encoding import force_text