Custom Scaler Type

Trying to use https://github.com/chadlieberman/graphql-type-long which allows for Long type.

Is there a way to use this?  Based on [mappingConverter](https://github.com/graphql-compose/graphql-compose-elasticsearch/blob/5ee582d1b9855cf64a871fd9f59cadf90834c8cf/src/mappingConverter.js) lines 149-151 + 201, it does not look like we can pass a custom type.

Am I wrong?