Fix ESM type import in Webpack loader

Closes GH-2452.

Reviewed-by: Christian Murphy <christian.murphy.42@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

packages/loader/index.cjs

@@ -1,10 +1,8 @@
 /**
  * @typedef {import('webpack').LoaderContext<unknown>} LoaderContext
+ * @typedef {import('./lib/index.js', {with: {'resolution-mode': 'import'}}).Options} Options
  */
 
-// @ts-expect-error: TS complains about CJS importing ESM but it works.
-/** @typedef {import('./lib/index.js').Options} Options */
-
 'use strict'
 
 // Note: we can’t export immediately, as TS generates broken types.