Add 'lib/*' to package.json exports

[TJKoury]

Working with versions > 2.5 has given me headaches as I am used to being able to import everything in this directory right into my code. Now I get the "./lib/xxxxxx.js' path is not exported" error.

Some large / very well known packages like Cesium use this pattern.

[gildas-lormeau]

People using zip.js could contact me if they have an issue with the library. I can fix them sometimes.

This issue should be fixed in the version 2.7.3 I've just published.

[TJKoury]

That was quick! Thanks so much

[gildas-lormeau]

You're welcome!