'LinkedIn' Campaign Type is missing in PHP SDK

[guptamrshashank]

Hi Team, 'LinkedIn' Campaign Type is missing from https://github.com/BingAds/BingAds-PHP-SDK/blob/main/src/V13/CampaignManagement/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