Fix the 3 missing UnitTests ColorConversion - brightness

[Chris53897]

There are actual 3 UnitTests that are failing.
https://github.com/neoteknic/Phue/runs/8056721561?check_suite_focus=true

These are all linked to the new option $bri (brightness)
https://github.com/neoteknic/Phue/blob/master/library/Phue/Helper/ColorConversion.php#L74

@neoteknic Can you please fix these as i do not know what the expected output is with the new variable?
But with the default value (null?) the result should have the same result as the original PhpUnit tests.