PubSub does not handle Raid Cancel events

[pilky]

I've been playing around with Raid events with PubSub and encountered a bug while testing. It seems Twitch is now sending a raid cancelled message which PubSub is not handling.

Unfortunately this also seems to cause further PubSub messages not to work. It seems to fail silently, but then throws an exception when I disconnect PubSub. I think the issue might be that RaidEvents switches on it's Type property, but that isn't set for the cancel event. I presume that's causing an exception that's breaking things further up stack.