Update nixpkgs

This gets rid of the call to the nixpkgs internal `_fromFetchGit`
because the `shallow = true` option has been adopted upstream.

Author: ibbem

default.nix

@@ -16,14 +16,7 @@ pkgs.stdenv.mkDerivation rec {
   src = with pkgs.lib.fileset;
     toSource {
       root = ./.;
-      # This should be `gitTracked ./.`. However, this currently doesn't accept
-      # shallow repositories as used in GitHub CI.
-      fileset =
-        (import (sources.nixpkgs + "/lib/fileset/internal.nix") {inherit (pkgs) lib;})._fromFetchGit
-        "gitTracked"
-        "argument"
-        ./.
-        {shallow = true;};
+      fileset = gitTracked ./.;
     };
 
   nativeBuildInputs = with pkgs; [

nix/sources.json

@@ -5,10 +5,10 @@
         "homepage": null,
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "a77ab169a83a4175169d78684ddd2e54486ac651",
-        "sha256": "0r9a87aqhqr7dkhfy5zrx2dgqq11ma2rfvkfwqhz1xqg7y6mcxxg",
+        "rev": "6832d0d99649db3d65a0e15fa51471537b2c56a6",
+        "sha256": "1ww2vrgn8xrznssbd05hdlr3d4br6wbjlqprys1al8ahxkyl5syi",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/a77ab169a83a4175169d78684ddd2e54486ac651.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/6832d0d99649db3d65a0e15fa51471537b2c56a6.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     }
 }