fix(types): allow typescript's new Node16 module resolution to find types

[bgotink]

TypeScript's new Node16 module resolution reads exports. It is currently looking for dist/index.d.ts or dist/index.d.mts as main types for uvu, and <export>/index.d.ts or <export>/index.d.mts for other exports depending on whether require or import is being used.

Setting the types export condition tells typescript where to find the correct types.

Closes #210, #211

[lukeed]

Thank you. Gotta love how TS created a bunch of pointless work for authors by purposefully disregarding a system that already worked for something new that also happens to flagrantly ignore the "exports" specs for conditions' ordering.