chore: Update ESLint to Version 9.0.0

[tocosastalo]

We need to update the ESLint configuration to new version 9.0.0. This update includes several key changes and improvements that are essential for maintaining code quality and consistency across the codebase.

Useful links:

• https://eslint.org/blog/2024/04/eslint-v9.0.0-released/
• https://typescript-eslint.io/blog/announcing-typescript-eslint-v7/

[tocosastalo]

This is blocked as Eslint 9 is supported from Next 15 - https://nextjs.org/blog/next-15#eslint-9-support.
First we need to finish #34