Disable one HLint warning

Problem: recent Hlint fails on Main.hs thinking that
enabling TemplateHaskell is redundant.

Solution: it seems to be a bug which is fixed upstream,
but the fixed version is not released yet.
So we just ignore that warning.

app/utf8-troubleshoot/Main.hs

@@ -40,6 +40,8 @@ import Data.Semigroup ((<>))
 
 import qualified Prelude as P
 
+-- See https://github.com/ndmitchell/hlint/commit/505a4d57b972f3ba605ad7a59721cef1f3d98a84
+{-# ANN module "HLint: ignore Unused LANGUAGE pragma" #-}
 
 -- | Encode a 'String' to be safe to print in ASCII-only.
 protect :: String -> String