title: Rails - Active Storage - Validates images certain dimensions?
body: <p>I found <a href="https://github.com/aki77/activestorage-validator" rel="nofollow noreferrer">gem activestorage-validator</a>, but is there a way of validating an attached image based on its dimensions?</p>
  <p>I essentially want to be able to block a user from attaching an image that can't cleanly be cropped/compressed (i.e. 3000px x 10px).</p>
  <p>Thanks!</p>