make sure the version of graphbook_code in the docker is the most up-to-date

[loftusa]

I just started a new docker run and it was using an old version of graphbook_code that was missing some imports. Checked that my docker pull neurodata/graphstatsbook:0.0.1 was up-to-date (it was). Possibly I was just running the wrong image (e.g., neurodata/graphstatsbook:latest). Need to double-check.