portfolio: add update script and make it nix-run-able (#199904)

pkgs/applications/office/portfolio/default.nix

···
 , makeDesktopItem
 , webkitgtk
 , wrapGAppsHook
+, writeScript
 }:
 let
   desktopItem = makeDesktopItem {
···
     ln -s $out/portfolio/icon.xpm $out/share/pixmaps/portfolio.xpm
   '';
 
+  passthru.updateScript = writeScript "update.sh" ''
+    #!/usr/bin/env nix-shell
+    #!nix-shell -i bash -p curl jq common-updater-scripts
+    version="$(curl -sL "https://api.github.com/repos/buchen/portfolio/tags" | jq '.[0].name' --raw-output)"
+    update-source-version portfolio "$version"
+  '';
+
   meta = with lib; {
     description = "A simple tool to calculate the overall performance of an investment portfolio";
     homepage = "https://www.portfolio-performance.info/";
     sourceProvenance = with sourceTypes; [ binaryNativeCode ];
     license = licenses.epl10;
     maintainers = with maintainers; [ elohmeier oyren shawn8901 ];
+    mainProgram = "portfolio";
     platforms = [ "x86_64-linux" ];
   };
 }