RESTful sensor for speech to text

Configuration
1

I am trying to set up the Google Cloud integration for speech to text not text to speech. However, my REST sensor isn’t working. It doesn’t even get created as a sensor. I have saved the json file mentioned in step 6 to the config folder.

Here is my configuration.yaml:

tts:
  - platform: google_cloud
    key_file: googlecloud.json

From these Google instructions, I put the following in sensors.yaml. I am not sure the syntax is fully correct.

- platform: rest
  name: "Speech to text"
  resource: https://speech.googleapis.com/v1/speech:recognize
  method: POST
  headers:
    Content-Type: application/json
    Authorization: Bearer $(gcloud auth application-default print-access-token)
  payload: '{ "config":"{"encoding":"WAV", "languageCode":"en-US"}", "audio":"{"uri":"https://www.signalogic.com/melp/EngSamples/Orig/ENG_M.wav"}" }'
  value_template: '{{ value_json }}'

Any ideas why this is not working?