fix: serialize Stripe checkout provisioning

docker/.env.production.example

@@ -48,6 +48,7 @@ MAIL_ENABLED=false
 MAIL_LOG_LINKS_WHEN_DISABLED=false
 # STRIPE_SECRET_KEY=sk_live_replace_me
 # STRIPE_WEBHOOK_SECRET=whsec_replace_me
+# STRIPE_API_BASE_URL=https://api.stripe.com
 # MAIL_PROVIDER=custom
 # MAIL_FROM=noreply@example.com
 # MAIL_PASSWORD=replace-with-smtp-authorization-code

docker/docker-compose.prod.yml

@@ -74,6 +74,7 @@ services:
       ADMIN_PASSWORD: ${ADMIN_PASSWORD:-}
       STRIPE_SECRET_KEY: "${STRIPE_SECRET_KEY:-}"
       STRIPE_WEBHOOK_SECRET: "${STRIPE_WEBHOOK_SECRET:-}"
+      STRIPE_API_BASE_URL: ${STRIPE_API_BASE_URL:-https://api.stripe.com}
       MAIL_ENABLED: ${MAIL_ENABLED:-false}
       MAIL_LOG_LINKS_WHEN_DISABLED: ${MAIL_LOG_LINKS_WHEN_DISABLED:-false}
       MAIL_PROVIDER: ${MAIL_PROVIDER:-qq}