chore(dev-deps): update @typescript-eslint to v6

Update the `@typescript-eslint/eslint-plugin` and
`@typescript-eslint/parser` plugin to v6.

The full list of changes needed can be found in the
[Announcing typescript-eslint v6 blog post][1], but the ones that
affect us are:
- Dropped support for Node.JS v14.
  This isn't a big deal for us, since Mermaid uses a version of
  `eslint-plugin-jsdoc` that does not support Node.JS v14 either,
  see 120029913d
  (chore(deps): update dependency eslint-plugin-jsdoc to v46, 2023-06-27)
- Changes to the `plugin:@typescript-eslint/recommended` configuration.
  I've manually changed the following two rules to match their old
  `@typescript-eslint/parser` v5 settings, to avoid turning ESLint
  warnings into errors:
  - `@typescript-eslint/no-explicit-any` to `warn`
  - `@typescript-eslint/no-unused-vars` to `warn`

[1]: https://main--typescript-eslint.netlify.app/blog/announcing-typescript-eslint-v6

.eslintrc.cjs

@@ -49,8 +49,10 @@ module.exports = {
     'no-unused-vars': 'off',
     'cypress/no-async-tests': 'off',
     '@typescript-eslint/consistent-type-imports': 'error',
+    '@typescript-eslint/no-explicit-any': 'warn',
     '@typescript-eslint/no-floating-promises': 'error',
     '@typescript-eslint/no-misused-promises': 'error',
+    '@typescript-eslint/no-unused-vars': 'warn',
     '@typescript-eslint/ban-ts-comment': [
       'error',
       {