Add an upper bound on h-s-e.

See #5.

Author: 23Skidoo

hackage-diff.cabal

@@ -84,7 +84,7 @@ executable hackage-diff
   -- other-extensions:
   build-depends:       base             >=4.8 && <5.0,
                        Cabal            >=1.20.0.0,
-                       haskell-src-exts >=1.15.0,
+                       haskell-src-exts >=1.15.0 && < 1.18,
                        ansi-terminal    >=0.6.1.1,
                        directory        >=1.2.0.0,
                        filepath         >=1.3.0.0,