PHP 8.2 Creation of dynamic property

Problem/Motivation

When I upgrade my dev environment to PHP 8.2, I see this warning:

Deprecated function: Creation of dynamic property Drupal\webpurify\WebPurifyAPI::$endpoint is deprecated in Drupal\webpurify\WebPurifyAPI->__construct() (line 57 of modules/contrib/webpurify/src/WebPurifyAPI.php).

In PHP 8.2. assigning values to class properties which are not declared is deprecated, and triggers a warning.

I'll provide a patch shortly.