update nix build system

default.nix

@@ -22,7 +22,7 @@ let
        walint.dontStrip = false;
      };
    }];
-   stack-sha256 = "16ilij2cygmwbdmjdzj6yl4yv7zi4qzwg7rxkxgp0hbjpkz6n42y";
+   stack-sha256 = "0ghwm2b81arypiypbbm2wza2f0cbqid7bm5qm93rr88pfavha2x1";
   };
 in
 {

nix/sources.json

@@ -5,10 +5,10 @@
         "homepage": "https://input-output-hk.github.io/haskell.nix",
         "owner": "input-output-hk",
         "repo": "haskell.nix",
-        "rev": "c2677deef14f2772110f56b60d74dee25f19902f",
-        "sha256": "0pa5n8lgq2hmsskyd7m4xsfiinq8mfpgw7g7ll3j77l5z4shi264",
+        "rev": "659b73698e06c02cc0f3029383bd383c8acdbe98",
+        "sha256": "0i91iwa11sq0v82v0zl82npnb4qqfm71y7gn3giyaixslm73kspk",
         "type": "tarball",
-        "url": "https://github.com/input-output-hk/haskell.nix/archive/c2677deef14f2772110f56b60d74dee25f19902f.tar.gz",
+        "url": "https://github.com/input-output-hk/haskell.nix/archive/659b73698e06c02cc0f3029383bd383c8acdbe98.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "niv": {