cosmic-greeter: add updateScript

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

@@ -11,6 +11,7 @@
   udev,
   coreutils,
   xkeyboard_config,
+  nix-update-script,
 }:
 
 rustPlatform.buildRustPackage (finalAttrs: {
@@ -68,6 +69,15 @@ rustPlatform.buildRustPackage (finalAttrs: {
     )
   '';
 
+  passthru.updateScript = nix-update-script {
+    extraArgs = [
+      "--version"
+      "unstable"
+      "--version-regex"
+      "epoch-(.*)"
+    ];
+  };
+
   meta = {
     homepage = "https://github.com/pop-os/cosmic-greeter";
     description = "Greeter for the COSMIC Desktop Environment";