Increase the priority of hook woocommerce_product_is_on_sale

Increase priority of woocommerce_product_is_on_sale hook.

add_action( 'plugins_loaded', function(){
  global $flycart_woo_discount_rules;
  if(!empty($flycart_woo_discount_rules)){
	  remove_filter('woocommerce_product_is_on_sale', array($flycart_woo_discount_rules->pricingRules, 'displayProductIsOnSaleTagOptimized'), 100, 3);
	  add_filter('woocommerce_product_is_on_sale', array($flycart_woo_discount_rules->pricingRules, 'displayProductIsOnSaleTagOptimized'), 1000, 3);
  }
});