PHP CURL 数组过滤器 - 日期变量

Question

<?php    $today = date("y-m-d");    $filter = ['2019-06-18'];    // Api Request    $a = ordersRequest("statistics/list", array("idapp" => 11111));    $links = $a['statistics']['grp_date'];    $filtered = array_filter($links, function ($item) use ($filter) {    return in_array($item['date'], $filter);    });    print_r($filtered);     ?>这个作品：$filter = ['2019-06-02'];但是我怎样才能在这个变量中获得当前日期？$filter = ['$today'];$filter = [$today];$filter = date("y-m-d");不适合我