cosmic-launcher: add updateScript

pkgs/by-name/co/cosmic-launcher/package.nix

@@ -5,6 +5,7 @@
   rustPlatform,
   just,
   libcosmicAppHook,
+  nix-update-script,
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -44,6 +45,15 @@ rustPlatform.buildRustPackage rec {
 
   env."CARGO_TARGET_${stdenv.hostPlatform.rust.cargoEnvVarTarget}_RUSTFLAGS" = "--cfg tokio_unstable";
 
+  passthru.updateScript = nix-update-script {
+    extraArgs = [
+      "--version"
+      "unstable"
+      "--version-regex"
+      "epoch-(.*)"
+    ];
+  };
+
   meta = {
     homepage = "https://github.com/pop-os/cosmic-launcher";
     description = "Launcher for the COSMIC Desktop Environment";