fix: update constant fields in item fields extension test

Author: alukach

tests/api/test_api.py

@@ -309,7 +309,7 @@ async def test_app_item_fields_extension(
 
     assert len(features) > 0
     # These fields are always included in items
-    constant_fields = ["type", "links", "assets", "collection", "stac_version"]
+    constant_fields = ["id", "collection", "links"]
     for item in features:
         assert set(item.keys()) == set(fields + constant_fields)