linting of readURL function

I disagree with the use of `<$>` in place of `.`, but not enough to fight hlint on it.

src/Network/Gemini/Capsule/Internal.hs

@@ -54,7 +54,7 @@ readURL
   -- ^ the connection
   -> IO (Maybe GemURL)
 readURL conn =
-  strFromConn inBufSize conn >>= return . \case
+  strFromConn inBufSize conn >>= return <$> \case
     Nothing  -> Nothing
     Just str -> decodeGemURL str