isExpired aborts payments that could pass on Stripe

Problem/Motivation

According to Stripe, It is possible for a card to be deducted even when it's expired.

If a card was saved to Stripe before it expired, it sometimes can continue to be charged after its expiration date has passed. The decision to allow the charge to go through is entirely up to the issuing bank...

Calling assertPaymentMethod in createPayment() checks for the card's expiry and prevents the payment attempt from going through.