Removed unnecessary depends arguments in setup.py
The point of a dependency in build systems is to declare that target X needs to be built before target Y. We use the depends keyword a lot, but list source files as the dependency. This is best case a no-op as we don't build source files, in the worst case these add complexity to the current and future build systems

@lithomas1  @WillAyd can you re-push to get circleci to run @lithomas1 thoughts here?  you've been doing a lot of build-related work lately Does modifying a header still trigger a rebuild? Ah that's a good point @lithomas1 and something I overlooked. We can just table this for now - hopefully the meson stuff won't be too far off anyway