Update fix_bond_react.cpp

  delete [] set;

  if (group) {

    std::string cmd = fmt::format("{} delete",master_group);

    group->assign(cmd);

    group->assign(std::string(master_group) + " delete");

    if (stabilization_flag == 1) {

      cmd = fmt::format("{} delete",exclude_group);

      group->assign(cmd);

      group->assign(std::string(exclude_group) + " delete");

      delete [] exclude_group;

    }

  }