Update langchain dependency in mongodb-rag-ingest package to be consistent with mongodb-rag-core

[velias]

mongodb-rag-ingest package is using very old langchain: ^0.1.16 dependency, which is inconsistent with newer @langchain/xzy used in mongodb-rag-core.

Relates to #455

[mongodben]

thanks for creating this. i think a tmp fix could be to share the langchain version in mongodb-rag-core, and only use that version in mongodb-rag-ingest

ex:

// some-mongodb-rag-ingest-file.ts

import langchain from "mongodb-rag-core"