upgrade django to 2.2 (#4620)

thirdpart/shibboleth/middleware.py

@@ -5,7 +5,7 @@ import logging
 from django.conf import settings
 from django.contrib.auth.middleware import RemoteUserMiddleware
 from django.core.exceptions import ImproperlyConfigured
-from django.core.urlresolvers import reverse
+from django.urls import reverse
 from django.http import HttpResponseRedirect
 from seaserv import seafile_api, ccnet_api
 
@@ -39,7 +39,7 @@ class ShibbolethRemoteUserMiddleware(RemoteUserMiddleware):
             raise ImproperlyConfigured(
                 "The Django remote user auth middleware requires the"
                 " authentication middleware to be installed.  Edit your"
-                " MIDDLEWARE_CLASSES setting to insert"
+                " MIDDLEWARE setting to insert"
                 " 'django.contrib.auth.middleware.AuthenticationMiddleware'"
                 " before the RemoteUserMiddleware class.")