Fix broken typescript compilation

[ianmarmour]

Typescript breaks on compilation because of an invalid use of reference types, see this documentation as to why the previous usage of reference types to refer to a relative path is invalid.

node_modules/graphql-compose-elasticsearch/lib/ElasticApiParser.d.ts:1:23 - error TS2688: Cannot find type definition file for 'src/types'.

1 /// <reference types="src/types" />
                        ~~~~~~~~~

Was able to remove this line locally and re-build and validated that this works fine and solves the build failures.