title: Cloud Firestore request from Postman
body: <p>I have created a Cloud Firestore database, with a collection and some documents. I want to make some requests to it with Postman, but I am not able to authenticate. I have created a service credentials and tried to get the token for the authentication, with no success. Any idea about how to get it? </p>
  
  <p>Which is the endpoint to get the token?</p>
  
  <p>Thanks in advance.</p>