Upgrade ESLint

[Serchinastico]

Hey,

I've been using this project for a while now and something that icks me is that it still installs ESLint v8 rather than v9. ESLint v8 is officially deprecated now as they say in their website: ESLint v8.x reached end-of-life on 2024-10-05 and is no longer maintained.

I know this comes with some other changes like flat list configs but I think it's worth to keep it up-to-date.

I'm willing to send a PR if you want, I wanted to chime in just in case it was something you didn't want to do in the project.

[satya164]

PR is welcome!