Mark this package as deprecated in favour of IAB's officially supported NPM package

[tuzz]

This package hasn't received updates in almost four years.

It no longer works with the latest vendor-list.json because the schema has changed:
https://vendor-list.consensu.org/v2/vendor-list.json

There seems to be an officially supported package for encoding/decoding from IAB:
https://www.npmjs.com/package/@iabtechlabtcf/core

There is an encoder/decoder tool built using this package here:
https://iabtcf.com/#/

I'd suggest we update the README of this package to point to that one instead.