uutils-diffutils: add defelo as maintainer

pkgs/by-name/uu/uutils-diffutils/package.nix

···
     homepage = "https://github.com/uutils/diffutils";
     license = lib.licenses.mit;
     mainProgram = "diffutils";
-    maintainers = with lib.maintainers; [ ];
+    maintainers = with lib.maintainers; [ defelo ];
     platforms = lib.platforms.unix;
   };
 })