Bump Grails version

[Aszusz]

Latest Grails version is now 4.0.10. This is probably the one we want to use.

[JoelProminic]

The current version is 3.3.10. Be aware that we have seen a lot of differences when upgrading to different major releases of Grails.

However, I think we are creating the new Grails project with a command like grails init, and we don't have a lot of custom code for Grails projects, so this update could be trivial.

[JoelProminic]

I confirmed that the only think in the Grails template is a template for the .grailsproj file. So, we should be able to generate a project with a different Grails version just by changing the configured Grails SDK, as long as the syntax is not changed for the Grails and Gradle commands that we use.