libsass: 3.5.3 -> 3.5.4

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/libsass/versions.

These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 3.5.4 with grep in /nix/store/xyyfnl8z6bsziqyibdk7am96h1dz8yiz-libsass-3.5.4
- directory tree listing: https://gist.github.com/68655a774ee14cf658d685eec8c1ab27

pkgs/development/libraries/libsass/default.nix

@@ -2,11 +2,11 @@
 
 stdenv.mkDerivation rec {
   name = "libsass-${version}";
-  version = "3.5.3";
+  version = "3.5.4";
 
   src = fetchurl {
     url = "https://github.com/sass/libsass/archive/${version}.tar.gz";
-    sha256 = "1lfdq2ahskf9yd0m71jlx3r4n6a0dhg4wxpnwbrvj2a23k7db7zi";
+    sha256 = "0w47hvzmbdpbjx8j83wn8dwcvglpab8abkszf9xfzrpqvb6wnqaz";
   };
 
   patchPhase = ''