Fix color higher than 255

[mixman68]

I had tried to fix colors, more info at : sqmk#114

require_once __DIR__ . '/vendor/autoload.php';

use \Phue\Helper\ColorConversion;

function testConvert($r,$g,$b) {
  $xy = ColorConversion::convertRGBToXY($r,$g,$b);
  
  $rgbConverted = ColorConversion::convertXYToRGB($xy["x"],$xy["y"],$xy["bri"]);
  echo "$r $g $b => {$rgbConverted['red']} {$rgbConverted['green']} {$rgbConverted['blue']}", PHP_EOL;
}

testConvert(255,0,0);
testConvert(200,50,0);
testConvert(200,50,0);
testConvert(243,50,6);
testConvert(200,143,68);
testConvert(233,230,211);
testConvert(33,232,11);
testConvert(2,32,113);
testConvert(98,23,234);

The conversion to XY is correct, same as other library excepted ignorance of Gamut of bulb
So i try to convert to XY and back to RGB
and i have these results :

255 0 0 => 254 0 0
200 50 0 => 200 50 0
200 50 0 => 200 50 0
243 50 6 => 242 50 6
200 143 68 => 200 143 68
233 230 211 => 233 230 211
33 232 11 => 33 232 11
2 32 113 => 2 34 119
98 23 234 => 97 23 232