github-desktop: add dtomvan as a maintainer

In response to https://github.com/NixOS/nixpkgs/pull/428716

pkgs/by-name/gi/github-desktop/package.nix

@@ -101,7 +101,7 @@ stdenvNoCC.mkDerivation (finalAttrs: {
     homepage = "https://desktop.github.com/";
     license = lib.licenses.mit;
     mainProgram = "github-desktop";
-    maintainers = [ ];
+    maintainers = with lib.maintainers; [ dtomvan ];
     platforms = lib.platforms.linux;
     sourceProvenance = with lib.sourceTypes; [ binaryNativeCode ];
   };