Support stripe/stripe-php:^7

Problem/Motivation

The Stripe module requires stripe/stripe-php as ^7.

https://git.drupalcode.org/project/stripe/-/blob/2.x/composer.json?ref_t...

This prevents Give from being installed.

Steps to reproduce

composer require drupal/give drupal/stripe

Proposed resolution

Update stripe version and review changes.

Remaining tasks

User interface changes

API changes

Data model changes