dj22: do not backport jsonb key transforms (#51516)

zoo/zoo_data/lookups.py

@@ -14,12 +14,15 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from django.contrib.postgres.fields import jsonb
+import django
+
 from django.db.models import Transform, TextField, DateField
 
-from django.conf import settings
-
-
+from django.contrib.postgres.fields import jsonb
+try:
+    from django.contrib.postgres.fields.jsonb import KeyTransform, KeyTransformTextLookupMixin
+except ImportError:
+    # backport from Django 2.x
     class KeyTransform(Transform):
         operator = '->'
         nested_operator = '#>'
@@ -45,16 +48,13 @@ class KeyTransform(Transform):
                 lookup = "%s" % self.key_name
             return "(%s %s %s)" % (lhs, self.operator, lookup), params
 
-
     jsonb.KeyTransform = KeyTransform
 
-
     class KeyTextTransform(KeyTransform):
         operator = '->>'
         nested_operator = '#>>'
         _output_field = TextField()
 
-
     class KeyTransformTextLookupMixin(object):
         """
         Mixin for combining with a lookup expecting a text lhs from a JSONField