Make Wraith spawn in other modes than Mixed

[SgtBriar]

Currently, Wraith only spawns in Mixed with a 10% chance. With mixed being the (if I recall correctly) rarest game mode as-is, this means we don't get to see Wraith much at all, which is a damn shame with it being so fun. What I propose is making Wraiths appear in Traitor and Changeling rounds with a 5% (or lower) chance, and maintain the 10% chance in Mixed.