DataLabels background method need a fix

[darkons]

Hello!

I'm sorry but I barely have time to make a PR

public function setDataLabelsBackground(array $dataLabelsBackground): Chart
{
    $this->dataLabelsBackground = $dataLabelsBackground;

    $this->setOption([
        'dataLabels' => [
            'enabled' => $dataLabelsBackground,
        ],
    ]);

    return $this;
}

enabled should be changed to background

Thank your for this package!