Postcode zipcode not required woocommerce

gistfile1.txt

function my_billing_postcode( $address_fields ) {
  $address_fields['postcode']['required'] = false;
  $address_fields['postcode']['label'] = "Posta Kodu";
  return $address_fields;
}
add_filter( 'woocommerce_default_address_fields', 'my_billing_postcode' );