fix(locale): don't try dynamically importing the default locale (#2098)

If `"en"` is passed as locale to the `<EmberFlatpickr />` component, the
addon will try importing a file `flatpickr/dist/l10n/en.js` which does
not exist as English is the default language that is included in the
core and doesn't need to be imported additionally.

ember-flatpickr/src/components/ember-flatpickr.ts

@@ -133,7 +133,7 @@ export default class EmberFlatpickr extends Component<EmberFlatpickrArgs> {
  Object.entries(rest).filter((entry) => entry[1] !== undefined),
  );
 
- if (typeof this.args.locale === 'string') {
+ if (typeof this.args.locale === 'string' && this.args.locale !== "en") {
  await import(`flatpickr/dist/l10n/${this.args.locale}.js`);
  }