fix test case for json type, and add allow_experimental_object_type setting to json field document.

Author: jayvynl

docs/Fields.md

@@ -646,6 +646,9 @@ Neither Nullable nor LowCardinality is supported.
 When query from the database, JSONField get dict or list.
 
 The JSON data type is an experimental feature. To use it, set `allow_experimental_object_type = 1` in the database settings.
+
+**Note:** From [ClickHouse 24.8 LTS](https://clickhouse.com/blog/clickhouse-release-24-08), set `allow_experimental_object_type = 1` to use JSON type.
+
 For example:
 
 ```python

tests/settings.py

@@ -47,6 +47,7 @@
                 "alter_sync": 2,
                 "allow_suspicious_low_cardinality_types": 1,
                 "allow_experimental_object_type": 1,
+                "allow_experimental_json_type": 1,
             },
         },
         "TEST": {"cluster": "cluster", "managed": False},
@@ -64,6 +65,7 @@
                 "alter_sync": 2,
                 "allow_suspicious_low_cardinality_types": 1,
                 "allow_experimental_object_type": 1,
+                "allow_experimental_json_type": 1,
             },
         },
         "TEST": {"cluster": "cluster", "managed": False},