Test the SerializeUTCTime property

src/AFRP.hs

@@ -390,9 +390,8 @@ data DelayState x a = DelayState
 instance (Serialize x, Serialize a) => Serialize (DelayState x a)
 
 newtype SerializeUTCTime = SerializeUTCTime UTCTime
-  deriving Eq
+  deriving (Eq, Show)
 
--- TODO: Needs '\x -> pure x == get (put x)' test
 instance Serialize SerializeUTCTime where
   put (SerializeUTCTime (UTCTime day time)) = do
     put (toModifiedJulianDay day)