handle addition/removal of fields gracefully

[sv]

File "/usr/local/lib/python3.11/site-packages/paradex_py/api/api_client.py", line 381, in fetch_system_config
    config = SystemConfigSchema().load(res)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/marshmallow_dataclass/__init__.py", line 910, in load
    all_loaded = super().load(data, many=many, **kwargs)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/marshmallow/schema.py", line 722, in load
    return self._do_load(
           ^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/marshmallow/schema.py", line 909, in _do_load
    raise exc
marshmallow.exceptions.ValidationError: {'environment': ['Unknown field.'], 'universal_deployer_address': ['Unknown field.']}