Typo in enum switche_service should be switched_service

[kevinzhow]

Today I received an exception log:
Data corrupted at path 'data.object.cancellationDetails.feedback'. Cannot initialize SubscriptionCancellationDetailsFeedback from invalid String value 'switched_service'.

I found that the error was caused by this.

stripe-kit/Sources/StripeKit/Billing/Subscriptions/Subscription.swift

Line 236 in 0c6ecd9

case switchService = "switch_service"

Please check the doc https://docs.stripe.com/api/subscriptions/cancel#cancel_subscription-cancellation_details-feedback