Не работает grequests, всегда возвращает None

with open("orders.txt") as werewolves: 
        array = [row.strip() for row in werewolves]
    print(array)
    url = 'https:/site.ru/update-order-price'
    headers = dict()
    headers['accept'] = 'application/json, text/plain, */*'
    headers['accept-encoding'] = 'gzip, deflate, br'
    headers['accept-language'] = 'ru-RU,ru;q=0.9,en-US;q=0.8,en;q=0.7'
    headers['user-agent'] = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.93 Safari/537.36'
    headers['content-type'] = 'application/json;charset=UTF-8'
    headers['cookie'] = 'x-auth-token=eyJ0eXAiOiJKV1QiLCJhbGci******'
    headers['origin'] = 'https://site.ru'
    rs = [grequests.post(url, json = {'order_id':{int(order)}, 'old_price':200 , 'new_price':350 , 'comment':'sale'} , headers = headers) for order in array]
    print(grequests.map(rs))