Support ESLint flat config

[alexeyr-ci]

Bug Description

ESLint special parser doesn't recognize eslint.config.js as an ESLint flat config file. Mostly it imports and uses packages like any other JS file, but compatibility features still may have dependencies in string literals similar to the old config.

Code snippets

Where the dependency is used:

// in eslint.config.js
const compat = new FlatCompat({
  baseDirectory: __dirname,
  recommendedConfig: js.configs.recommended,
});

const airbnb = compat.extends('airbnb');

Where the dependency is listed in package.json:

// devDependencies
"eslint-config-airbnb": "^19.0.4",

This also applies to import resolvers etc. See https://github.com/eslint/eslintrc?tab=readme-ov-file#usage-esm for details on FlatCompat.

Versions

• node -v: v18.17.0
• npm -v: 9.6.7
• depcheck --version: 1.4.7

Extra info

Sorry for filing quite a few bugs! But I hope this will be the last one for now.

BONUS POINTS: If you wish to help us debug further, the depcheck --json option will show more information. Check here in the README for documentation on json output.