message: Export jsonapi-serializer
  Even though the JSONAPISerializer class is now deprecated, it still needs to be exported from the package.
diff: export { JSONAPISource as default } from './jsonapi-source';
  export * from './jsonapi-source';
  +export * from './jsonapi-serializer';
  export * from './serializers/jsonapi-base-serializer';
  export * from './serializers/jsonapi-document-serializer';
  export * from './serializers/jsonapi-operation-serializer';
  