Be able to set expire date time when requesting invoice

[aaronkopplin]

Hi there, I would like to be able to request an expiry date time when creating an invoice.

What I am currently running into is that an invoice requested from one vendor expires in 1 minute, whereas an invoice requested from another vendor expires in 1 hour. I would need a least an hour to coordinate the settling of the invoices and I dont see a way currently to request an expiry time or minimum timespan until expiry using this library.

[dolcalmi]

@aaronkopplin is this part of LUDs?