Refund struct missing failure_reason

[jredl-va]

When implementing the stripe refund webhook it seems as though failure_reason is missing from the struct: https://github.com/stripe/stripe-go/blob/master/refund.go#L48

Link to the documentation: https://stripe.com/docs/api/refunds/object

Is there any specific reason that this field is excluded?
Would you accept a PR adding this field?

[remi-stripe]

@jredl-va No specific reason except that we must have missed that field. I can take the fix if you want but we would definitely love a PR if you're up for doing the work :)

[jredl-va]

If you have the time it would be most appreciated. We have for the time being implemented our own proxy object that contains this field when unmarshalling.

[remi-stripe]

@jredl-va This was fixed in 62.5.0, thanks again for the report!

[jredl-va]

Thanks for the quick turn around!