Create a phone number for a person

curl --request POST \
  --url https://api.slant.app/v1/people/{person_id}/phone_numbers \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "phone_number": "+15555551234",
  "extension": "1234",
  "phone_type": "mobile",
  "is_primary": true
}
'

{
  "id": "<string>",
  "person_id": "<string>",
  "phone_number": "<string>",
  "extension": "<string>",
  "phone_type": "<string>",
  "is_primary": true
}