Update `prisma` dependency to a recent version (4.7.x or higher)

[TasinIshmam]

This project is currently using an older version of Prisma. Since it's a popular and useful reference project for using PlanetScale, Prisma and Next.js, I was wondering if it would be possible to upgrade Prisma to the latest version.

I recommend using Prisma version 4.7.0 or higher since in 4.7.0, the Relation mode feature (previously known as Referential Integrity) went GA.

You can learn more about this change in the Prisma Relation mode documentation and release notes for 4.7.0. For further context, this Pull request shows the update made to the PlanetScale docs related to this.

You can also learn more about upgrading to Prisma version 4 in the Prisma documentation.