site.hs: Fix build failure

Fix gitlab ci build failures. See
https://jaspervdj.be/hakyll/tutorials/faq.html#hgetcontents-invalid-argument-or-commitbuffer-invalid-argument

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>

site.hs

@@ -2,9 +2,12 @@
 {-# LANGUAGE OverloadedStrings #-}
 import           Data.Monoid (mappend)
 import           Hakyll
+import qualified GHC.IO.Encoding as E
 --------------------------------------------------------------------------------
 main :: IO ()
-main = hakyllWith config $ do
+main = do
+    E.setLocaleEncoding E.utf8
+    hakyllWith config $ do
     match "images/*" $ do
         route   idRoute
         compile copyFileCompiler