A Dart HTTP service meant to be deployed to Cloud Run and which uses the Cloud Firestore features in package:googleapis.

• Increments a counter stored in Cloud Firestore via a transaction.
• Based on package:shelf.
• Includes a number of useful APIs in lib/helpers.dart which can be copied and used in other projects.
• Follow instructions at https://cloud.google.com/run/docs/quickstarts/build-and-deploy to build and deploy on Cloud Run.
• To deploy this demo, you will also need to enable the Cloud Firestore API.