Commit diff is using old class syntax

[Ducasse]

[jecisc]

I know there is another issue about that somewhere.

But IIRC it is not sosimple to switch because the syntax is rooted into Monticello and Ring.

The change should be done, but it is not a simple change I think

[jecisc]

Linked issue: https://github.com/pharo-project/pharo/issues/15974