idpv5 CAS proxy tickets service identifer

[Cantor, Scott]

> Unless I'm missing it, I don't see any mention of this change
> in the release notes. I'm guessing not many people use CAS
> proxy support :), but this change can break stuff, so it might
> be worth a bullet point.

I don't know what the issue is/was and don't really have time to learn the protocol. If someone drafts text that's suitable, I'll add it to the page (though I think it may technically be editable anyway).

-- Scott