PHP 8 compatibility: change wakeup magic methods to public visibility

src/Admin/MarketingBord.php

@@ -34,7 +34,7 @@ private function __clone() {
  /**
  * Singleton instance can't be serialized.
  */
- private function __wakeup() {
+ public function __wakeup() {
  }
 
  public function display_marketing_bord() {

src/Admin/Requirements.php

@@ -47,7 +47,7 @@ private function __clone() {
  /**
  * Singleton instance can't be serialized.
  */
- private function __wakeup() {
+ public function __wakeup() {
  }
 
  /**

src/Orders/Orders.php

@@ -41,7 +41,7 @@ private function __clone() {
  /**
  * Singleton instance can't be serialized.
  */
- private function __wakeup() {
+ public function __wakeup() {
  }
 
  /**

src/Products/Products.php

@@ -38,7 +38,7 @@ private function __clone() {
  /**
  * Singleton instance can't be serialized.
  */
- private function __wakeup() {
+ public function __wakeup() {
  }
 
  public function get_list_args() {