Update dotenv-expand (again) to 5.x to resolve previously closed issues

Created by: kireerik

issue to resolve: https://github.com/facebook/create-react-app/issues/4002 (This is was probably never resolved (https://github.com/facebook/create-react-app/blob/master/CHANGELOG-2.x.md#203-october-1-2018 https://github.com/facebook/create-react-app/pull/4009) or could be a regression.)

@gaearon, @iansu As we can see dotenv-expand is not up to date: https://github.com/facebook/create-react-app/blob/fbb3b03ba59d5e67aa91ab2e706a988cb521eb58/packages/create-react-app/yarn.lock.cached#L3250-L3251

https://github.com/motdotla/dotenv-expand/commit/f012c66432f48a057f395f4c7cbde6dc1383f013