Support for MX country on connecting with Stripe

[calo001]

Stripe recently arrived officially in Mexico, and I tried to connect with the dashboard and got a 500 error. Now MX accounts should be fully supported in Stripe. https://stripe.com/mx/blog/stripe-launches-in-mexico

Mexico is in the PREVIEW_COUNTRIES array in this code: https://github.com/elementary/houston/blob/master/src/houston/passport/stripe.js#L32

Thanksss 🙏️

[arshubham]

Same for India too. Although it still shows in preview, according to stripe it can process charges in USD. https://stripe.com/docs/currencies