[w3c/browser-payment-api] Make ISO4217 an informative reference rather than normative (#242)

The spec currently has no normative dependency on ISO4217 so it should only be an informative reference not a normative one.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/browser-payment-api/issues/242