Include `stdint.h` in Kaleidoscope-Ranges.h

This makes it unnecessary to include `Arduino.h` (or `stdint.h`, or some other
header that includes it) before including Kaleidoscope-Ranges.h.

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

plugins/Kaleidoscope-Ranges/src/Kaleidoscope-Ranges.h

@@ -17,6 +17,8 @@
 
 #pragma once
 
+#include <stdint.h>  // for uint16_t
+
 // Included for definition of legacy Macros plugin key range:
 #include "kaleidoscope/key_defs.h"