Contrast should return an int or float?

[NiklasBr]

Function signature says : float

color/src/Contrast.php

Line 7 in 2a3bb4e

public static function ratio(Color $a, Color $b): float

but the return value is cast to int:

color/src/Contrast.php

Lines 27 to 31 in 2a3bb4e

	if ($l1 > $l2) {
	return (int) (($l1 + 0.05) / ($l2 + 0.05));
	} else {
	return (int) (($l2 + 0.05) / ($l1 + 0.05));
	}

It could be improved by changing the return cast to (float), but I am not sure if there are any side effects to I want to ask about what is the intent here before creating a PR.