Detected by my citgm workflow ;).

We throw now FST_ERR_HOOK_INVALID_ASYNC_HANDLER when async function calls are having a callback.
Removing the done parameter so that we pass the tests again ;).

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct