build(deps): bump google.com/cloudsdktool/google-cloud-cli from 503.0.0-emulators to 504.0.1-emulators in /docker/images/pubsub-emulator

build(deps): bump google.com/cloudsdktool/google-cloud-cli from 503.0.0-emulators to 504.0.1-emulators in /docker/images/pubsub-emulator #871