'LinkedIn' Campaign Type is missing in PHP REST SDK

[shashank-dyninno]

Hi Team, 'LinkedIn' Campaign Type is missing from https://github.com/BingAds/BingAds-PHP-REST-SDK/blob/main/src/Model/CampaignManagementService/CampaignType.php

although its available in https://ui.ads.microsoft.com/ portal, please update sdk code or let us know next release date/ETA with this change.