ESLint v9

[mrholek]

I'm upgrading ESLint to version 9.x in my Bootstrap-based project. Are you planning to upgrade ESLint as well? If so, I can create a pull request.

[julien-deramond]

I suppose we'll upgrade to ESLint 9.x at some point, but I don’t have a timeline for it yet. @XhmikosR is the one handling dependencies and configuration updates, so he’d have more insight into any potential issues. Let’s maybe wait for his feedback before moving forward.