fix(ia): endpoint updates

[miguelpeixe]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Update Donate Block API endpoints from Automattic/newspack-plugin#3564

Instructions at Automattic/newspack-plugin#3564

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[dkoo]

Almost missed this one! I think it still needs some slight adjustments, see below.

[miguelpeixe]

Thanks for catching those, @dkoo!