Update README.md

Co-authored-by: Alessio Zampatti <[email protected]>

Author: AlexandrosMor

README.md

@@ -5,7 +5,7 @@ This is the officially supported Python library for using Adyen's APIs.
 ## Integration 
 The library supports all APIs under the following services:
 
-* [Checkout API](https://docs.adyen.com/api-explorer/#/CheckoutService/v67/overview): Our latest integration for accepting online payments. Current supported version:  **v67**
+* [Checkout API](https://docs.adyen.com/api-explorer/#/CheckoutService/v68/overview): Our latest integration for accepting online payments. Current supported version:  **v68**
 * [Payments API](https://docs.adyen.com/api-explorer/#/Payment/v64/overview): Our classic integration for online payments. Current supported version:  **v64**
 * [Recurring API](https://docs.adyen.com/api-explorer/#/Recurring/v49/overview): Endpoints for managing saved payment details. Current supported version:  **v49**
 * [Payouts API](https://docs.adyen.com/api-explorer/#/Payout/v64/overview): Endpoints for sending funds to your customers. Current supported version:  **v64**