Test 3D Secure and make sure it works

[vdavid]

I'm concerned that it doesn't work with the current Stripe solution we've switched to. I didn't take any particular care about 3D Secure when I implemented the checkout flow.

Stripe has 3D Secure-enabled test cards: https://docs.stripe.com/testing#regulatory-cards, so it's easy to test.

This page could also help: https://docs.stripe.com/payments/3d-secure/authentication-flow#three-ds-cards

[chenkc805]

This is not a priority, moving to P3.

[vdavid]

Tested it, it doesn't work:

Thanks for setting the priority, @chenkc805!