types(update): wrap metadata param in `Partial`

Problem

This PR makes it so that you don't need to supply all of the required fields in your custom metadata interface when updating a vector using the TS client.

For example, say I have a metadata interface defined as the following:

interface MyMetadata {
  title: string;
  source: string;
  isArchived?: boolean;
}

I want to update the value for isArchived, but I want to leave the values for title and source as is. I'd write the following code, but I get a type error because no value for title or source were provided

const ns = pinecone.index<MyMetadata>(indexName).namespace(namespace);
await ns.update({ id: "abc123", metadata: { isArchived: true });

Type '{ isArchived: boolean; }' is missing the following properties from type '{ title: string; source: string; isArchived?: boolean | undefined; }': title, source

Solution

By wrapping the generic in Partial, we make it so that all of the fields in the interface are optional which is the intent of this method according to the documentation

If set_metadata is included, the values of the fields specified in it will be added or overwrite the previous value.

Type of Change

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update
[ ] Infrastructure change (CI configs, etc)
[ ] Non-code change (docs, etc)
[ ] None of the above: (explain here)

Test Plan

N/A

pinecone-io / pinecone-ts-client