fix(pkg): add types to package.json#exports (agilgur5#126)

In TS 4.7+, when using newer `moduleResolution` options such as `node16`, `bundler`, and `nodenext`, the types _must_ be defined in `package.json#exports` to be properly detected

Author: daltonkyemiller

package.json

@@ -7,7 +7,8 @@
   "module": "dist/index.mjs",
   "exports": {
     "require": "./dist/index.umd.min.js",
-    "default": "./dist/index.mjs"
+    "default": "./dist/index.mjs",
+    "types": "./dist/index.d.ts"
   },
   "typings": "dist/index.d.ts",
   "files": [