libimagequant: 2.12.1 -> 2.12.2

Semi-automatic update generated by
https://github.com/ryantm/nixpkgs-update tools. This update was made
based on information from
https://repology.org/metapackage/libimagequant/versions

pkgs/development/libraries/libimagequant/default.nix

···
 with stdenv;
 
 let
-  version = "2.12.1";
+  version = "2.12.2";
 in
   mkDerivation {
     name = "libimagequant-${version}";
···
       owner = "ImageOptim";
       repo = "libimagequant";
       rev = "${version}";
-      sha256 = "0r7zgsnhqci2rjilh9bzw43miwp669k6b7q16hdjzrq4nr0xpvbl";
+      sha256 = "1k61ifcjbp2lcrwqidflj99inkyhpbrw0hl1nzq1rjp5dnw2y5lw";
     };
 
     preConfigure = ''