Add Promotion code parameter to SetupPaymentSheetParameters

[Tom3652]

Is your feature request related to a problem? (please describe)
I would like to be able to add a promotion code to a subscription.
Currently there is no way to pass the promotion code to Stripe.instance.initPaymentSheet.

Describe the solution you'd like
I would like to have a new parameter in SetupPaymentSheetParameters that is called promotionCode that displays the equivalent of this field from the Stripe documentation :

Describe alternatives you've considered
Designing a custom UI to enter a promo code before showing Stripe modal and use it inside the backend as a separate request to check if the promotion exists.

Additional context
Thanks for the package !

[jonasbark]

Please upvote this ticket:
stripe/stripe-react-native#1130

[Tom3652]

Done !
In the meantime i have managed to make it work with my backend

[hamzalakrati]

+1 for this feature !