Generated Latest Changes for v2021-02-25 (GiftCard endpoints and new transaction error support)

[recurly-integrations]

Added support for Gift Cards feature of Recurly API, new methods added to the client to consume the gift card endpoints:

• List gift cards - ListGiftCards
• Create gift card - CreateGiftCard
• Fetch a gift card - GetGiftCard
• Preview gift card - PreviewGiftCard
• Redeem gift card - RedeemGiftCard

Added support for transaction error

• Added decline_code to transactionError