Continue step-up challenge

curl --request POST \
  --url https://{appId}.session.prelude.dev/v1/session/stepup/continue \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "challenge_token": "<string>",
  "verification_token": "<string>"
}
'

{
  "challenge_token": "<string>",
  "public_key_credential_request_options": {
    "challenge": "<string>",
    "timeout": 123,
    "rpId": "<string>",
    "allowCredentials": [
      {
        "type": "public-key",
        "id": "<string>",
        "transports": [
          "<string>"
        ]
      }
    ]
  }
}