Update README

README.md

@@ -27,7 +27,7 @@ Have a look at the [example folder](/example) for more.
 Find the most current documentation of the Saferpay JSON API here:<br>
 https://saferpay.github.io/jsonapi/
 
-This library is currently based on v1.20 of the Saferpay JSON API.
+This library is currently based on v1.31 of the Saferpay JSON API.
 
 ## Contribution
 You are [welcome to contribute](/.github/contributing.md) to this repo.