gdc --version doesn't indicate which D front-end version it's compatible with

[singingbush]

Seems I cannot use gdc currently. It turns out that gdc-11.2.1 
(which is the one in Fedora 35 repo) still has D frontend at 
2.076 and I have multiple dependencies that cannot compile with 
that version. Hopefully when GDC 12 lands projects will start 
testing against it in their CI builds.