Remove "TODO" from colorsys undocumented notice

The float constants `ONE_SIXTH`, `ONE_THIRD`, and `TWO_THIRD` are
intentionally undocumented, so a "TODO" on the comment stating
as such is unnecessary.

Author: Andrew5057

stdlib/colorsys.pyi

@@ -9,7 +9,7 @@ def hls_to_rgb(h: float, l: float, s: float) -> tuple[float, float, float]: ...
 def rgb_to_hsv(r: float, g: float, b: float) -> tuple[float, float, float]: ...
 def hsv_to_rgb(h: float, s: float, v: float) -> tuple[float, float, float]: ...
 
-# TODO: undocumented
+# undocumented
 ONE_SIXTH: Final[float]
 ONE_THIRD: Final[float]
 TWO_THIRD: Final[float]