PHP 8.4 deprecation: Implicitly marking parameter as nullable

Problem/Motivation

Drupal 11.1 is compatible with PHP 8.4 but the Consumers module currently triggers a deprecation warning:

Deprecated: Drupal\consumers\Negotiator::negotiateFromRequest(): Implicitly marking parameter $request as nullable is deprecated, the explicit nullable type must be used instead in /opt/drupal/web/modules/consumers/src/Negotiator.php on line 112