title: date-fns format is not localizing numbers
body: <p>I want to convert a time string to Arabic. For example I want to convert <code>10:00 PM</code> to <code>مساءاً ١٠:٠٠</code>. I am using <code>format</code> function with <code>locale</code>.</p>
  <pre><code>import ar from 'date-fns/locale/ar-SA'
  ...
  
  str = format(date, 'h:mm a', {locale: ar})
  </code></pre>
  <p>But it gives a string like this <code>10:00 م</code>. Basically digits are not getting translated.</p>