Add exports field to package.json

[perrin4869]

This solves rollup/plugins#1130
Bundling json-bigint with rollup fails without this change.

[shuckster]

Just wanted to say that the ordering of the exports and the inclusion of a default can make a difference to WebPack and esbuild, as I recently discovered with my own small modules.

[MikeMcl]

Looks good. I'll consider it.

See #300 for previous on exports.

[ShenHongFei]

LGTM
Fixed type error for TypeScript nodenext module type

[MikeMcl]

Okay, thank you.

[coldcode001]

@MikeMcl Is there any plan to publish a new release containing this fix? I'm waiting for this to fix a critical webpack issue, would appreciate if it can be released soon.

[MikeMcl]

@coldcode001

Published v9.1.0.

Thanks for the nudge.