It seems like GitHub Actions went slower in the last months since we
sometimes observe a problem when our `autobahn-server` is not started
quickly enough which leads to the autobahn suite trying to connect to
the server that is not yet running resulting into failed pipeline.
See https://github.com/snapview/tokio-tungstenite/runs/6658266507?check_suite_focus=true
According to the documentation from the Autobahn Suite GitHub page, it
seems like they do not support Python 3 which is currently the default
Python version used with our GitHub Actions.
The simplest way to workaround it properly seems to be using the Docker
image that the maintainers of the project suggest to use for running the
suite. This is more future-proof way that we should rely upon.
This commit also removes some redundant steps that are not required.
Daniel Abramov