Add PromptPay support (#5)

* Handle PromptPay QR flow

* Send billing email for PromptPay

* fix isort

* Update payment.py

* Update signals.py

---------

Co-authored-by: Chondaen <chondaen12@1000WA>

src/pretix/plugins/stripe/views.py

@@ -595,7 +595,7 @@ class ScaView(StripeOrderView, View):
 
         if intent.status == 'requires_action' and intent.next_action.type in [
             'use_stripe_sdk', 'redirect_to_url', 'alipay_handle_redirect', 'wechat_pay_display_qr_code',
-            'swish_handle_redirect_or_display_qr_code', 'multibanco_display_details',
+            'swish_handle_redirect_or_display_qr_code', 'multibanco_display_details', 'promptpay_display_qr_code',
         ]:
             ctx = {
                 'order': self.order,
@@ -613,6 +613,8 @@ class ScaView(StripeOrderView, View):
             elif intent.next_action.type == 'multibanco_display_details':
                 ctx['payment_intent_next_action_redirect_url'] = intent.next_action.multibanco_display_details['hosted_voucher_url']
                 ctx['payment_intent_redirect_action_handling'] = 'iframe'
+            elif intent.next_action.type == 'promptpay_display_qr_code':
+                ctx['payment_intent_promptpay_image_url'] = intent.next_action.promptpay_display_qr_code['image_url_svg']
 
             r = render(request, 'pretixplugins/stripe/sca.html', ctx)
             r._csp_ignore = True