The Simplicité platform version 5.1 is now available on the version 5 template’s Git repository release[-light] branches and as Docker images tagged 5-latest[-light].
Check the the release note for details.
Note that the version 5.1 includes some minor compatibility-breaking changes vs version 5.0, make sure you have reviewed them prior to upgrading.
Also note that, due to system model changes it is not possible to revert an upgraded instance to version 5.1 back to version 5.0.