Update MonadSt to have Monad superclass (#45)

Author: JordanMartinez

src/Control/Monad/ST/Class.purs

@@ -7,7 +7,7 @@ import Control.Monad.ST.Global (Global)
 import Control.Monad.ST.Global as Global
 import Effect (Effect)
 
-class MonadST s m | m -> s where
+class Monad m <= MonadST s m | m -> s where
   liftST :: ST s ~> m
 
 instance monadSTEffect :: MonadST Global Effect where