fix colorwheel location
Apparently _pixelbuf no longer has colorwheel in it (https://github.com/adafruit/circuitpython/issues/4992). But it does live in the builtin rainbowio lib,
@@ -4,7 +4,7 @@ import digitalio
import rotaryio
import neopixel
import keypad
-from _pixelbuf import colorwheel
+from rainbowio import colorwheel
key_pins = (board.KEY1, board.KEY2, board.KEY3, board.KEY4, board.KEY5, board.KEY6,
