Add a field to store the number of turns played in a round

src/Hanafuda/Message.hs

@@ -175,6 +175,7 @@ data PublicState = PublicState {
     , river :: Hanafuda.Pack
     , step :: KoiKoi.Step
     , trick :: [Hanafuda.Card]
+    , turns :: Int
     , rounds :: [(PlayerID, KoiKoi.Score)]
   } deriving Generic