chars: add updateScript (#336954)

pkgs/tools/text/chars/default.nix

@@ -2,6 +2,7 @@
 , fetchFromGitHub
 , rustPlatform
 , Security
+, nix-update-script
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -19,6 +20,10 @@ rustPlatform.buildRustPackage rec {
 
   buildInputs = lib.optionals stdenv.hostPlatform.isDarwin [ Security ];
 
+  passthru = {
+    updateScript = nix-update-script { extraArgs = [ "--version=branch" ]; };
+  };
+
   meta = with lib; {
     description = "Commandline tool to display information about unicode characters";
     mainProgram = "chars";