Remove module field in package.json

[dcastil]

The module field was used for ESM builds by bundlers before there was type: module, but because of type: module, the module field never became a standard. Instead, package exports can be used to define entry points for different environments which I already use.

As module is not a standard and bundlers and Node 12+ support the exports field, there is no reason to keep it.

More info:

• https://stackoverflow.com/questions/42708484/what-is-the-module-package-json-field-for/42817320#42817320
• https://esbuild.github.io/api/#main-fields:~:text=CommonJS%2Dstyle%20module.-,module,-This%20field%20came

[github-actions]

This was addressed in release v2.0.0.