fix: Resolve config modules with ESM createRequire()

ES modules do not have require() available, we must construct it first.
This fixes the CLI when passing `--config my-config-package`, broken in
v12.0.0.

The tests didn't catch this because Jest still doesn't support mocking
ESM, and there's really no way to write a test for this right now.

lib/loadConfig.js

@@ -1,5 +1,6 @@
 /** @typedef {import('./index').Logger} Logger */
 
+import { createRequire } from 'module'
 import { pathToFileURL } from 'url'
 
 import debug from 'debug'
@@ -8,6 +9,12 @@ import YAML from 'yaml'
 
 const debugLog = debug('lint-staged:loadConfig')
 
+/**
+ * require() does not exist for ESM, so we must create it to use require.resolve().
+ * @see https://nodejs.org/api/module.html#modulecreaterequirefilename
+ */
+const require = createRequire(import.meta.url)
+
 /**
  * The list of files `lint-staged` will read configuration
  * from, in the declared order.