Update async-synthesis-long-form-audio.md

Author: Yueying-Liu

articles/cognitive-services/Speech-Service/quickstarts/text-to-speech/async-synthesis-long-form-audio.md

@@ -56,7 +56,7 @@ This code gets a list of available voices that you can use to convert text-to-sp
 ```python
 parser = argparse.ArgumentParser(description='Text-to-speech client tool to submit voice synthesis requests.')
 parser.add_argument('--voices', action="store_true", default=False, help='print voice list')
-parser.add_argument('-key', action="store", dest="key", required=True, help='the speech subscription key, like ff1eb62d06d34767bda0207acb1da7d7 ')
+parser.add_argument('-key', action="store", dest="key", required=True, help='the speech subscription key, like fg1f763i01d94768bda32u7a******** ')
 parser.add_argument('-region', action="store", dest="region", required=True, help='the region information, could be centralindia, canadacentral or uksouth')
 args = parser.parse_args()
 baseAddress = 'https://%s.customvoice.api.speech.microsoft.com/api/texttospeech/v3.0-beta1/' % args.region