Patch package.json to fix TS type exports. (#150)

* fix: typescript export

* use top level types

* format

---------

Co-authored-by: Aaron Yarborough <aaron@alienjungle.digital>
Co-authored-by: Yao Ding <yaodingyd@users.noreply.github.com>

package.json

@@ -10,6 +10,7 @@
   "module": "./dist/react-flickity-component.es.js",
   "exports": {
     ".": {
+      "types": "./src/index.d.ts",
       "import": "./dist/react-flickity-component.es.js",
       "require": "./dist/react-flickity-component.umd.js"
     }