Create promotion

Seed example (keychains curl)

npx -y keychains@latest curl "https://supply-xml.booking.com/hotels/xml/promotions" \
  -X POST \
  -H "Content-Type: application/xml" \
  -H "Accept: application/xml" \
  -H "Authorization: Basic {{BOOKING_SECRET}}" \
  -d '<request>\n  <hotel_id>{{$hotel_id}}</hotel_id>\n  <promotion>\n    <name>{{$title}}</name>\n    <type>{{$type}}</type>\n    <target_channel>{{$target_channel}}</target_channel>\n    <min_stay_through>{{$min_stay_through}}</min_stay_through>\n    <non_refundable>{{$non_refundable}}</non_refundable>\n    <book_date>\n      <start>{{$book_start}}</start>\n      <end>{{$book_end}}</end>\n    </book_date>\n    <stay_date>\n      <start>{{$stay_start}}</start>\n      <end>{{$stay_end}}</end>\n      <active_weekdays>\n        <active_weekday>{{$weekday}}</active_weekday>\n      </active_weekdays>\n      <excluded_dates>\n        <excluded_date>{{$excluded_date1}}</excluded_date>\n        <excluded_date>{{$excluded_date2}}</excluded_date>\n      </excluded_dates>\n    </stay_date>\n    <additional_dates>\n      <additional_date>{{$additional_date1}}</additional_date>\n      <additional_date>{{$additional_date2}}</additional_date>\n    </additional_dates>\n    <rooms>\n      <room id="{{$room_id_1}}"/>\n      <room id="{{$room_id_2}}"/>\n    </rooms>\n    <parent_rates>\n      <parent_rate id="{{$parent_rate_id_1}}"/>\n      <parent_rate id="{{$parent_rate_id_2}}"/>\n    </parent_rates>\n    <discount value="{{$discount}}"/>\n  </promotion>\n</request>'