How do I resolve DNSvalidation error on Heroku

Using Laravel validator, I tried to validate email using the email validator format like this

'email' => 'required|email:dns'

It's working locally after editing my php.ini file but when hosted on heroku it throws some error. Here is the error message

The Egulias\EmailValidator\Validation\DNSCheckValidation class requires the Intl extension.

Please how do I resolve this?