Wrong type for amount field -> PaymentCreateRequest

[Arthurmtro]

https://github.com/gocardless/gocardless-nodejs/blob/3b46dfe2a23dd7f4ba01ac9423f8f7bb651d18b0/src/services/paymentService.ts#L17

In the documentation we can see that the field is a number but in the package it's a string who is wrong ^^

https://developer.gocardless.com/direct-debit/taking-a-one-off-payment