Update TypeScript exports to support moduleResolution bundler

[kwangure]

moduleResolution: "bundler" is a recent setting added to TypeScript to support bundler setups. It's the setting you should probably be using when bundling code. With this setting TypeScript only searches for types in the exports field of the package.json.

It requires the following change:

 "exports": {
   "import": "./dist/index.js",
   "require": "./dist/index.cjs",
+  "types": "./dist/index.d.ts"
 },

[marijnh]

Should already work as of 426fe04