Overwriting the existing cache with the new initialState

[CopyJosh]

Been looking at different projects to gather some best practice ideas for implementing apollo and next, and came across your project which I have found very helpful -- thank you.

Assuming it was similarly inspired by the with-apollo example in the NextJS repo, this pull request updates a change that was made and documented here - https://github.com/vercel/next.js/pull/32733/

Hope it's helpful.