Update generated code

[stripe-openapi]

Codegen for openapi v1268.

Changelog

• Add support for new resources Billing.CreditBalanceSummary, Billing.CreditBalanceTransaction, Billing.CreditGrant, and Margin
• Add support for retrieve method on resource CreditBalanceSummary
• Add support for all and retrieve methods on resource CreditBalanceTransaction
• Add support for all, create, expire, retrieve, update, and void_grant methods on resource CreditGrant
• Rename usage_threshold_config to usage_threshold on Billing.Alert
• Remove support for filter on Billing.Alert
• Add support for pretax_credit_amounts on CreditNote
• Add support for total_pretax_credit_amounts on Invoice
• Add support for new value international_transaction on enum Treasury.ReceivedCredit.failure_code