Binaries in project’s own f-droid repo out of date

[lukasfink1]

The project’s own f-droid repo still supplies the builds from last year (4.5.1). This issue is different from #39 in that—at least I assume—it would be possible to fix, as it doesn’t concern the slow to update main f-droid repo.

[linsui]

Because https://github.com/c3nav/c3nav-android/blob/master/current_version is not updated.