Add a List member

curl --request POST \
  --url https://api.twitter.com/2/lists/{id}/members \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "user_id": "2244994945"
}'

{
  "data": {
    "is_member": true
  },
  "errors": [
    {
      "detail": "<string>",
      "status": 123,
      "title": "<string>",
      "type": "<string>"
    }
  ]
}