use nixpkgs sliding sync package

pkgs/matrix-sliding-sync/default.nix

@@ -1,37 +0,0 @@
-{ lib
-, buildGoModule
-, fetchFromGitHub
-}:
-
-buildGoModule rec {
-  pname = "matrix-sliding-sync";
-  version = "0.99.11";
-
-  src = fetchFromGitHub {
-    owner = "matrix-org";
-    repo = "sliding-sync";
-    rev = "refs/tags/v${version}";
-    hash = "sha256-Wd/nnJhKg+BDyOIz42zEScjzQRrpEq6YG9/9Tk24hgg=";
-  };
-
-  vendorHash = "sha256-0QSyYhOht1j1tWNxHQh+NUZA/W1xy7ANu+29H/gusOE=";
-
-  subPackages = [ "cmd/syncv3" ];
-
-  ldflags = [
-    "-s"
-    "-w"
-    "-X main.GitCommit=${src.rev}"
-  ];
-
-  # requires a running matrix-synapse
-  doCheck = false;
-
-  meta = with lib; {
-    description = "A sliding sync implementation of MSC3575 for matrix";
-    homepage = "https://github.com/matrix-org/sliding-sync";
-    license = with licenses; [ asl20 ];
-    maintainers = with maintainers; [ emilylange ];
-    mainProgram = "syncv3";
-  };
-}

sliding-sync/default.nix

@@ -11,7 +11,7 @@ in
 
     package = lib.mkOption {
       type = lib.types.package;
-      default = pkgs.callPackage ../pkgs/matrix-sliding-sync { };
+      default = pkgs.matrix-sliding-sync;
       description = "What package to use for the sliding-sync proxy.";
     };