gtk4 vapi: Fix Expression.evaluate value parameter
See attachment. I couldn't fork the repo to make a merge request directly.
Don't hesitate to fix/propose a different fix.
I don't really know how to test the change properly, but overriding the vapi locally in the project I've been working on with the only difference being the ref
value worked just fine.
I ran vapigen
to re-generate the API file, but since it was against Gtk 4.10, I only picked the relevant change.