build(deps): bump next and react-email

Removes [next](https://github.com/vercel/next.js). It's no longer used after updating ancestor dependency [react-email](https://github.com/resend/react-email/tree/HEAD/packages/react-email). These dependencies need to be updated together.


Removes `next`

Updates `react-email` from 2.1.4 to 4.2.12
- [Release notes](https://github.com/resend/react-email/releases)
- [Changelog](https://github.com/resend/react-email/blob/canary/packages/react-email/CHANGELOG.md)
- [Commits](https://github.com/resend/react-email/commits/react-email@4.2.12/packages/react-email)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 
  dependency-type: indirect
- dependency-name: react-email
  dependency-version: 4.2.12
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]