STRIPES-820 include missing dependencies
STRIPES-820 include missing dependencies

It's another entry for the "how did this ever work?" category. `core-js`
and `regenerator-runtime` are both used in `./src/index.js` and yet were
never included as deps in `package.json`. How ...?

Refs STRIPES-820

folio-org/stripes-core,folio-org/stripes-core,folio-org/stripes-core