jest-environment-node peer dependency

[ntraut]

Should we add the jest-environment-node dev dependency along with jest-mongodb? It is written nowhere in the doc, but yarn complains about that:

warning " > @shelf/[email protected]" has unmet peer dependency "[email protected] || 28.x || 29.x".

This peer dependency was added in the commit c99c17d, so it should be useful for the yarn Plug'n'Play mode.