Create: script to fetch a list of all current editors

[kaiyamag]

In order to generate a list of available editors, current-reviewsdata.ipynb` currently has a static list of editors' GitHub handles. To avoid needing to update this list when new editors are added, it would be helpful to use the GitHub API to get a list of all possible editors' handles.

[lwasser]

you read my mind @kaiyamag

rest endpoint is here:

we could add a helper to the pyosmeta library as well to do this but maybe we develop it here using pygithub ✨