In the spirit of making the entire website as explicit and managed as possible, I'm happy to add this to the deploy script if you'd like (e.g. as per the /artwork directory). Just need to know where to get the file from to begin with.
@CiaranG, @eighthave, anyone else know where this file comes from, and perhaps how often it is updated?
We should move to using the official Debian base box, and not our custom one. But that's not trivial, it'll take some work. So I'd close this issue in favor of fdroidserver#359