* Improve support for refunds in preparation for work in CiviCRM core (#15476-15479).
* Add CiviCRM version info to stripe customer - this is useful when troubleshooting issues on client sites as it is important to know whether a reported issue may have been fixed in a later version.
* Fix [#110](https://lab.civicrm.org/extensions/stripe/issues/110) -Allow submit if amount is 0.
* Fix and record paymentIntents for recurring contributions - show authentication to user on thankyou page.
> this checks loads 3d secure etc from Stripe if required.