PHP 8.4 Deprecation: explicit nullable type must be used

Problem/Motivation

Deprecated function: Drupal\webform_ip_geo\Plugin\WebformElement\WebformIpGeo::replaceTokens(): Implicitly marking parameter $webform_submission as nullable is deprecated, the explicit nullable type must be used instead in include() (line 576 of /app/vendor/composer/ClassLoader.php)

PHP 8.4 best practices dictate we declare this as possibly being nullable. To extend the PHP compatibility for the must versions of PHP, we can use the PHP 7.1 added support for nullable types, which introduced the ?TYPE syntax to declare the types as nullable

see https://php.watch/versions/8.4/implicitly-marking-parameter-type-nullabl...