feat: add CommonJS support alongside ESM

[hujiulong]

Description

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Fixes #26 🦕

The build process now uses tsup, resulting in the following output:

- dist
  - index.js
  - index.cjs
  - index.d.ts
  - index.d.cts

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[hujiulong]

Hi @swapydapy,

When you have a moment, could you please review my PR? Your feedback would be greatly appreciated. Thank you!