[Chore] Cleanup npm package

[yhnavein]

chore: remove unnecessary files from the npm package

This PR does not contain any change to the logic or the implementation. It is only reducing size of npm package by excluding files that are not necessary for a standard usage of this library.

Before: 6KB gzipped (22 KB and 21 files unpacked)
After: 4KB gzipped (11 KB and 5 files unpacked)

It may be a small change but for 7M downloads weekly this is suddenly ~56 GB less of data transfer per month.

New tarball contents

Tarball Contents
----------------
1.1kB LICENSE
4.2kB README.md
4.0kB index.js
1.1kB package.json
932B types/index.d.ts

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

[Uzlopak]

@jsumners PTAL

[Eomm]

Thank you for your interest in this topic. Please see the discussion in fastify/skeleton#42 (comment) for my reasoning against such a change.

[mcollina]

Here is a video explanation too: https://youtu.be/D18jlN2JNE0?si=iDKR6g9JZh4iLUk3