build: update to ESLint 8

[Robbert]

The ESLint 8 release notes mention The /lib entrypoint has been removed, which is the reason the current release of eslint-mdx is not compatible with ESLint 8. We experience the following error:

Oops! Something went wrong! :(

ESLint: 8.0.1

Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Failed to load plugin 'mdx' declared in '.eslintrc.json#overrides[1]': Package subpath './lib/rules/no-unused-expressions' is not defined by "exports" in /github.com/nl-design-system/utrecht5/node_modules/eslint/package.json
Referenced from: /github.com/nl-design-system/utrecht5/.eslintrc.json
    at new NodeError (node:internal/errors:371:5)
    at throwExportsNotFound (node:internal/modules/esm/resolve:440:9)
    at packageExportsResolve (node:internal/modules/esm/resolve:692:3)
    at resolveExports (node:internal/modules/cjs/loader:482:36)
    at Function.Module._findPath (node:internal/modules/cjs/loader:522:31)
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:919:27)
    at Function.Module._load (node:internal/modules/cjs/loader:778:27)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (/github.com/nl-design-system/utrecht5/node_modules/v8-compile-cache/v8-compile-cache.js:159:20)
    at Object.<anonymous> (/github.com/nl-design-system/utrecht5/node_modules/eslint-plugin-mdx/lib/rules/no-unused-expressions.js:7:57)

The maintainer of eslint-mdx is already working on ESLint 8 compatibility, so we'll have to wait for that to upgrade:
mdx-js/eslint-mdx#353 Their work is much appreciated, I'm really looking forward to the new release.

[JounQin]

@Robbert Hi, can you help to try yarn add -D https://pkg.csb.dev/mdx-js/eslint-mdx/commit/519fbe5b/eslint-plugin-mdx to help us to confirm whether that PR is working as expected?

I try it in my personal packages, it's working.

[Robbert]

Resolved by #480