highlight: 4.14 -> 4.15 (#371976)

pkgs/tools/text/highlight/default.nix

···
 let
   self = stdenv.mkDerivation rec {
     pname = "highlight";
-    version = "4.14";
+    version = "4.15";
 
     src = fetchFromGitLab {
       owner = "saalen";
       repo = "highlight";
       rev = "v${version}";
-      hash = "sha256-UxbgYspocoy9ul2dhIhvIwqKMeWSG7vJY1df3UkgpHQ=";
+      hash = "sha256-CpbVm5Z9cKPQdOzBNOXsgrX3rfC6DTVE7xfmOAshbEs=";
     };
 
     enableParallelBuilding = true;