Bumps langchain version, fixes upsert type error

[prosocres]

I recently forked the repo, followed the Quickstart guide and received an error on step 4 ("Generate embeddings"):

PineconeArgumentError: The argument to upsert had type errors: argument must be array.

Did a little digging and think it may have been caused by the Pinecone and Langchain upgrade cycles:

• When the package.json file was bumped on Jun 7, the Pinecone major version was bumped from '0' to '2' (see commit log)
• As part of Pinecone's major version 1 release they made changes to upsert (see migration guide)
• Later versions of Langchain appear to be compatible with this change, but some of the interim versions (for example, 0.0.214) had dev dependency conflicts with Pinecone 2.2.2
• So even though the package.json file has minor version support via the semver notation - "langchain": "^0.0.100", - the package-lock.json file suggested it was still only using langchain version 0.0.100

Solution: Bumping the package.json dependency to "langchain": "^0.1.37" resolved the type error and allowed me to run the app in dev mode.

Not sure if anyone else had this issue or is able to replicate it but thought I would share what worked for me.

[prosocres]

@ykhli and @timqian - I'm not sure I have permission to add reviewers so thought I would direct this to you since you are listed in the "Code contribution workflow" section of the README.md file.