Project's Language Bar Doesn't Recognize Raku

In Short

I use the Raku language - the fork of Perl- and it doesn't show-up in the bar, the bar isn't exists at all because of that.

I'd thought to find a repository of language file extensions for GitLab to issue that, but haven't found that.
Also tried to fix it via .gitattributes, but that isn't works too.

The Project — esalebu/InteractiveStorytelling

— Why I Want That

To decide: delete or fix the file of attributes; add a badge that Raku is used or don't.