Add llvm-hs-pretty package

Fix prettyprinter version conflict

src/Main.hs

@@ -3,7 +3,7 @@
 module Main where
 
 import qualified Data.Text.IO as T
-import Prettyprinter
+import Data.Text.Prettyprint.Doc (pretty)
 import Text.Megaparsec (parse)
 import Windows12.Parser (programP)
 

src/Windows12/Ast.hs

@@ -3,7 +3,7 @@
 module Windows12.Ast where
 
 import Data.Text (Text)
-import Prettyprinter
+import Data.Text.Prettyprint.Doc
 
 data BinOp
   = Add