DIN5008: Twig deprecated attribute()

[kevinpapst]

Hi @LiaraAlis

Twig is deprecating the attribute() function, see: https://github.com/twigphp/Twig/blob/3.x/doc/deprecated.rst

You are using it in your DIN5008 template: https://github.com/kimai/invoice-templates/blob/main/din5008-invoice/din5008-invoice.pdf.twig#L321

Maybe it can simply be replaced with array syntax?

<th class="invoice-details-label">{{ lineData[0] }}:</th>
<td class="invoice-details-value">{{ lineData[1] }}</td>