Replaces a broadcast's tag actions with the supplied set (a full replace, not an incremental add). A tag action applies or removes tags when a contact opens the broadcast or clicks a link in it. actions must be present: the array you send becomes the broadcast's complete rule set, and any rule not re-sent is removed. Send [] to remove all of them. Every tag UUID must belong to a tag in the authenticated account -- if any one does not, the request is rejected with 422 and the broadcast keeps the rules it already had. actions was previously an optional field on update_broadcast, which now rejects it. Its shape is unchanged; only its home and the fact that it is required have changed.