Consider the file in package.json types not to be unused

[fcostarodrigo]

In a lib written in JS with the type declared in an index.d.ts referenced in the package.json types field, knip reports index.d.ts as unused.

It would be nice if knip would recognize that this file is used because it exports the types.

Stack Blitz example: https://stackblitz.com/edit/stackblitz-starters-q7yeyg (run npm test)