Replace get_class() call, deprecated since PHP 8.3 (#514)

application/plugins/Plugin_controller.php

@@ -43,7 +43,7 @@ function __construct($login = TRUE)
 		$this->plugin_name = strtolower(get_class($this));
 
 		// Prevent this controller from being called directly
-		if (get_class() === get_class($this))
+		if (__CLASS__ === get_class($this))
 		{
 			redirect(site_url('/'), 'location', 301);
 		}