[EIP-1193] Test onramp-kit

[yagopv]

Context / issue

As part of the EIP-1193 implementation, we need to retest all the related kits. This involves analyzing, executing, and updating the unit tests, integration tests, related example apps, and playgrounds.

Proposed solution

In the onramp-kit

• Check the unit tests for the Monerium pack
• Check the unit tests for the Stripe pack
• Check the example application continue to work

Additional context

#651