update to Babel 8

[jkhartshorne]

Babel 7 has some dependencies that may not be compatible with Node 14. Babel 8 should be out at some point in 2020, so we need to watch for this and upgrade when we can.

Hopefully in the meantime it won't cause poblems.

[jkhartshorne]

create-react-app has some of the same problems for the same reasons.