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

[kireerik]

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

@gaearon, @iansu As we can see dotenv-expand is not up to date:

create-react-app/packages/create-react-app/yarn.lock.cached

Lines 3250 to 3251 in fbb3b03

	dotenv-expand@4.2.0:
	version "4.2.0"

motdotla/dotenv-expand@f012c66

[heyimalex]

You're sure this is still happening? The bug was in dotenv, not dotenv-expand, and we're currently pinned to dotenv 6.2.0 so that fix definitely landed.

[kireerik]

Yes, I am.

The issue was in dotenv-expand: #4002 (comment)

This is the exact commit with the resolution in the dotenv-expand repository: motdotla/dotenv-expand@f012c66

[kireerik]

#5833 (comment)

[kireerik]

motdotla/dotenv-expand#18 (comment)

@heyimalex I found an open pull request: #7531

This would solve the issue.

[heyimalex]

Forgive me :)