Typescript workers don't work with ESM

Thank you for this library!

Using [Typescript Workers](https://threads.js.org/usage#typescript-workers-in-nodejs) with `"type": "module"` in `package.json` produces an error:
```
Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /home/alexk/code/threads-ts-node-esm-issue/src/worker.ts
require() of ES modules is not supported.
```

See reproduction https://github.com/lynxtaa/threads-ts-node-esm-issue