chore: make the UMD bundle be the main bundle

package.json

@@ -4,8 +4,7 @@
   "description": "Restrict inputs to certain valid characters (e.g. formatting phone or card numbers)",
   "author": "Braintree <code@getbraintree.com> (https://www.braintreepayments.com/)",
   "license": "MIT",
-  "main": "main.js",
-  "browser": "./dist/restricted-input.js",
+  "main": "dist/restricted-input.js",
   "homepage": "https://github.com/braintree/restricted-input",
   "repository": {
     "type": "git",