Github Action for the Network-Runner

It would be great if there were a `Github-action` for the network-runner! Obviously, it would be nice to add a one-liner to workflows to make the cli available. Still, even more importantly, Dependabot can be used with GitHub-actions to ensure we're on the latest version! 

Currently, I have to wait for tests to fail in `avalanche-rs` before realizing I need to update the dependency manually. 