You can now use latest instead of a numbered version in a REST API
URI. Your request is routed to the most recent REST API version that is supported by your org.
This is indicated in the response of the List Available REST API Versions resource.
Where: This change applies to Lightning Experience and Salesforce Classic in API Enabled Group, Professional, Enterprise, Performance, Unlimited, Developer, and Database.com editions.
How: In a REST API URI, as seen in the following example, replace the version segment
vXX.0 with latest.
https://<MyDomainName>.my.salesforce.com/services/data/latest/sobjects/Account