Bump next and @eventcatalog/core

Removes [next](https://github.com/vercel/next.js). It's no longer used after updating ancestor dependency [@eventcatalog/core](https://github.com/event-catalog/eventcatalog). These dependencies need to be updated together.


Removes `next`

Updates `@eventcatalog/core` from 1.2.7 to 2.18.1
- [Release notes](https://github.com/event-catalog/eventcatalog/releases)
- [Changelog](https://github.com/event-catalog/eventcatalog/blob/main/CHANGELOG.md)
- [Commits](https://github.com/event-catalog/eventcatalog/compare/@eventcatalog/[email protected])

---
updated-dependencies:
- dependency-name: next
  dependency-type: indirect
- dependency-name: "@eventcatalog/core"
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>