Accept variable amounts with Stripe Checkout using PHP

In this livestream, I answered a request from one of our users to show how to take variable amount donations with Stripe Checkout using php. We use the `price_data` attribute to create Price objects on the fly.

We show how to use metadata, accept different currencies, and talked a bit about associating an existing Stripe customer object with new Checkout Sessions.

Code! https://github.com/cjavilla-stripe/checkout-php-variable