Fazer o campo de número do endereço aceitar apenas números

example.php

<?php

add_filter( 'woocommerce_checkout_fields' , 'lpb_change_address_number_field_input_type', 999 );
function lpb_change_address_number_field_input_type ( $fields ) {
  $fields['billing']['billing_number']['type'] = 'number';
  $fields['shipping']['shipping_number']['type'] = 'number';

  return $fields;
}