Update donation platform and donation button

[jglovier]

The prior donation solution, GoFundMe Charity, had some issues (a test donation of $50 was never received by Hope Ministries), and I received an email at some point saying that the service was no longer going to be supported (although by the landing page on their website it looks like it is still active 🤷).

The donation button no longer points to a Hope Ministries fundraiser, and since they never received the test donation I think it would be best to find a different platform.

GiveButter is one alternate with zero fees.