CONTRIBUTING: fix gcloud login command - gcloud auth login
@@ -28,7 +28,7 @@ write and run the tests in any modified directories.
## Running system tests
1. Set the `GOLANG_SAMPLES_PROJECT_ID` environment variable to a suitable test project.
-1. Ensure you are logged in using `gcloud login` or set the `GOOGLE_APPLICATION_CREDENTIALS` environment variable to the path of your credentials file.
+1. Ensure you are logged in using `gcloud auth login` or set the `GOOGLE_APPLICATION_CREDENTIALS` environment variable to the path of your credentials file.
Tests are authenticated using [Application Default Credentials](https://developers.google.com/identity/protocols/application-default-credentials).
1. Install the test dependencies:
