PHP 8.4: Fix implicit nullable parameter deprecations in Client.php

[asipple1]

When running with PHP 8.4, the following deprecation warnings are triggered:

Deprecated: Brightcove\API\Client::HTTPRequest(): Implicitly marking parameter $extraconfig as nullable is deprecated, the explicit nullable type must be used instead in /vendor/brightcove/api/lib/Brightcove/API/Client.php on line 170

Deprecated: Brightcove\API\Client::request(): Implicitly marking parameter $post as nullable is deprecated, the explicit nullable type must be used instead in /vendor/brightcove/api/lib/Brightcove/API/Client.php on line 322

Ref: https://wiki.php.net/rfc/deprecate-implicitly-nullable-types

brightcove-api-php84-nullable-params.patch