增加月份跳月

        $firstday = date('Y-m-01', strtotime($time));

        $lastDay = date('Y-m-d', strtotime("$firstday +1 month -1 day"));

//laravel

 $this->dateStart = $time->copy()->startOfMonth();

  $this->dateEnd =  $time->copy()->endOfMonth();

再增加月份