set orders to complete

ordercomplete.php

<?php

add_filter( 'woocommerce_payment_complete_order_status', 'growdev_order_payment_complete_order_status', 10, 2 );

function growdev_order_payment_complete_order_status( $order_status, $order_id ) {
  $order = wc_get_order( $order_id );

  if ( 'processing' == $order_status &&
       ( 'pending' == $order->status ) ) {

       $order_status = 'completed';
    }

  return $order_status;
}