implemented stripCRLF

src/Network/Gemini/Capsule/Internal.hs

@@ -132,7 +132,10 @@ readMax maxLen conn = do
 -- | Strips the CR/LF characters from the end of a string, retuning
 -- Nothing if they are not present
 stripCRLF :: String -> Maybe String
-stripCRLF = undefined
+stripCRLF = \case
+  ""     -> Nothing
+  "\r\n" -> Just ""
+  c:str  -> (c:) <$> stripCRLF str
 
 readLoop :: Int -> S.InputStream BS.ByteString -> MaybeT IO Builder
 readLoop maxLen src = lift (S.read src) >>= \case