Make generated code compatible with PHP 8.4

[v-noskov]

The current code in the codegen folder produces deprecation errors on PHP 8.4. For instance:

  1x: HubSpot\Client\Marketing\Transactional\Api\SingleSendApi::__construct(): Implicitly marking parameter $client as nullable is deprecated, the explicit nullable type must be used instead

To be fully compatible with PHP 8.4, it should be generated by Open API Generator v.7.12 or higher.

[ksvirkou-hubspot]

Hi everyone
It has been regenerated in the latest version.

[v-noskov]

@ksvirkou-hubspot Thanks