Docker::Event is missing the "Scope" attribute

[danschmidt5189]

The Moby project's Event schema defines a "Scope" attribute, a string valued either:

1. "local" to indicate a non-Swarm scoped event, such as a container exit.
2. "swarm" to indicate a Swarm scoped event, such as a service update.

Git-blame shows that Scope was added eight years ago, so adding it to Docker::Event shouldn't introduce any incompatibilities.

[danschmidt5189]

Opened a PR for this (see link above). Is the pipeline broken? All of the podman tests fail as well as some of the docker tests, but for reasons totally unrelated to the PR.