Superflous header include

[SteveRussell33]

I can't do a PR for this as I've already got a PR staged for the upstream eurorack repo. But just to let you know there's an #include (line 39 or 44) that can be removed from:

eurorack/stages/segment_generator.h

Lines 39 to 44 in a5b21c1

	#include "stages/modes.h"
	#include "stmlib/utils/random.h"
	#include "stages/quantizer.h"
	#include "stages/oscillator.h"
	#include "stages/variable_shape_oscillator.h"
	#include "stages/modes.h"