Restrict Django version to <6 (#1560)

Fixes the CI.

Author: superlevure

setup.py

@@ -64,7 +64,7 @@
         "graphene>=3.0,<4",
         "graphql-core>=3.1.0,<4",
         "graphql-relay>=3.1.1,<4",
-        "Django>=3.2",
+        "Django>=3.2,<6",
         "promise>=2.1",
         "text-unidecode",
     ],