[BUG] BillingRequestMandateRequest defined twice

[dreinon]

Hi!
BillingRequestMandateRequest interface is defined twice in the file, and this leads to exporting only the second.

The implementations are the following:

// first

/** Type for a billingrequestmandaterequest resource. */
export interface BillingRequestMandateRequest {
    currency: string;
    scheme?: string;
}


// second

/** Type for a billingrequestmandaterequest resource. */
export interface BillingRequestMandateRequest {
    currency: string;
    links: BillingRequestMandateRequestLinks;
    scheme?: string;
    verify: BillingRequestMandateRequestVerify;
}

The difference between them is that the second has links and verify property, which I have looked for in the API Reference in the docs, and regarding to the links property, I haven't found any mandate_request[links], and regarding to the verify property, it appears in the introduction of the Billing Requests Section.

The first definition appears in the create billing request endpoint section.

Thanks!

[brettwillis]

Duplicate of #116 which is closed by #120