Update to ESLint 9

[wrslatz]

Is your feature request related to a problem?

The project currently uses ESLint 8. ESLint 8 is now EOL and unsupported.

Describe the solution you'd like

The project should use ESLint 9 for linting.

Describe alternatives you've considered

No response

Additional context

vercel/next.js#64409 has been completed. It will be released as part of Next 15 soon. There is no info on support coming to Next 14, so this may require a major version update of Next at the same time.

[wrslatz]

Attempting to update right now results in peer dependency conflicts

❯ npm i
npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR! 
npm ERR! While resolving: private-mirrors@0.1.0
npm ERR! Found: @typescript-eslint/eslint-plugin@7.16.1
npm ERR! node_modules/@typescript-eslint/eslint-plugin
npm ERR!   dev @typescript-eslint/eslint-plugin@"8.13.0" from the root project
npm ERR!   @typescript-eslint/eslint-plugin@"^5.4.2 || ^6.0.0 || ^7.0.0 || ^8.0.0" from eslint-config-next@14.2.15
npm ERR!   node_modules/eslint-config-next
npm ERR!     dev eslint-config-next@"15.0.2" from the root project
npm ERR!   1 more (typescript-eslint)
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! dev @typescript-eslint/eslint-plugin@"8.13.0" from the root project
npm ERR! 
npm ERR! Conflicting peer dependency: @typescript-eslint/parser@8.13.0
npm ERR! node_modules/@typescript-eslint/parser
npm ERR!   peer @typescript-eslint/parser@"^8.0.0 || ^8.0.0-alpha.0" from @typescript-eslint/eslint-plugin@8.13.0
npm ERR!   node_modules/@typescript-eslint/eslint-plugin
npm ERR!     dev @typescript-eslint/eslint-plugin@"8.13.0" from the root project

We'll need to wait for full support to release.

[wrslatz]

When ready to update, these resources will be helpful

• https://eslint.org/docs/latest/use/migrate-to-9.0.0
• https://eslint.org/docs/latest/use/configure/migration-guide

[wrslatz]

Depends on #263