Create attribute

curl --request POST \
  --url https://api.us.poly.ai/v1/agents/{agentId}/branches/{branchId}/attributes \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "name": "<string>"
}
'

{
  "id": "<string>",
  "name": "<string>"
}