fix(developer_manual): Add TaskProcessing updates to 33 upgrade guide

see nextcloud/server#56908

see nextcloud/server#56717

Signed-off-by: Marcel Klehr <mklehr@gmx.net>

[skip ci]

Author: marcelklehr

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_33.rst

@@ -202,6 +202,8 @@ Changed APIs
 
 - The ``setId`` and ``getId`` methods of ``\OCP\BackgroundJob\IJob`` were changed to return/accept a string instead of an int. Same for ``\OCP\BackgroundJob\IJobList`` were some methods (``removedById``, ``getById`` and ``getDetailsById``) are now taking a string instead of an int. The string is suppose to be a snowflake id.
 - The ``setObjectId`` and ``getObjectId`` methods of ``\OCP\Activity\IEvent`` were changed to return/accept a string in addition to an int. The string is suppose to be a snowflake id.
+- The ``\OCP\TaskProcessing\Task`` class now has ``getIncludeWatermark`` and ``setIncludeWatermark`` methods for indicating whether the provider should add a watermark to the generated output.
+- The TaskProcessing OCS API now also accepts the ``includeWatermark`` flag when scheduling tasks
 
 Deprecated APIs
 ^^^^^^^^^^^^^^^