CommonJS support

[kaijiel24]

Is it possible to build and release a CommonJS version of this library on NPM?

[hildjj]

I don't want to have both in the same package, due to the dual-import risk. Having a separate package would work, but it would be a little bit painful to set up. I'd potentially take a PR on this.

See #57 for other work in this space.

[hildjj]

Note that since node 20.1, you can require('cbor2'), and it works, as long as you aren't using jest.