Export types as well

Fix:

```
Could not find a declaration file for module 'add-to-calendar-button-react'. 'node_modules/add-to-calendar-button-react/dist/atcb.js' implicitly has an 'any' type.
  There are types at 'node_modules/add-to-calendar-button-react/dist/index.d.ts', but this result could not be resolved when respecting package.json "exports". The 'add-to-calendar-button-react' library may need to update its package.json or typings.

import { AddToCalendarButton } from "add-to-calendar-button-react"
```

I checked the related issues from this main issue and the common way to fix it, is by exporting the types as well: microsoft/TypeScript#52363

Author: cabello

package.json

@@ -16,6 +16,7 @@
   "types": "./dist/index.d.ts",
   "exports": {
     ".": {
+      "types": "./dist/index.d.ts",
       "import": "./dist/atcb.js",
       "require": "./dist/atcb.umd.cjs"
     }