Duckling encoding umlauts

Question

I apply duckling for extracting and converting written numbers into digits. when I pass the sentence in german: " fünf sechs sieben", it triggered an error: {'message': 'An invalid response was received from the upstream server'}

do you know how can I encode the sentence to avoid the error? Sentences without german "umlauts" are working fine.

url = "https://duckling..../parse"

payload = f'locale=de_DE&text={input_transcript}&dims=number'
headers = {
        "Content-Type": "application/x-www-form-urlencoded; charset=UTF-8"
    }

try:
        response = requests.post(
            url,
            data=payload,
            headers=headers,
        )
        if response.status_code == 200:
           json_response = response.json()