endgame-singularity: remove unused updater and use tag instead of rev (#418552)

pkgs/by-name/en/endgame-singularity/package.nix

···
   unzip,
   python3,
   enableDefaultMusicPack ? true,
-  unstableGitUpdater,
 }:
 
 let
···
   main_src = fetchFromGitHub {
     owner = "singularity";
     repo = "singularity";
-    rev = "8bbc2322ad1a0e83f78f5af731dfa97b6bd63f9c";
-    hash = "sha256-HiFE746JtGjZJbiKhB3ubfb376tJmz78jUfdu3/RQic=";
+    tag = "v${version}";
+    hash = "sha256-wYXuhlGp7gisgN2iRXKTpe0Om2AA8u0eBwKHHIYuqbk=";
   };
 
   music_src = fetchurl {
···
           "$(echo $out/lib/python*/site-packages/singularity)/music"
           # ↑ we cannot glob on [...]/music, it doesn't exist yet
   '';
-
-  passthru = {
-    # for the updater
-    src = main_src;
-    updateScript = unstableGitUpdater {
-      tagPrefix = "v";
-    };
-  };
 
   meta = {
     homepage = "http://www.emhsoft.com/singularity/";