Add Tobias Kuban to list of contributors

Merged username-removed-124398 requested to merge NicoAlt/fdroid-website:add-Tobias-Kuban into master

As requested here: https://gitlab.com/fdroid/fdroid-website/issues/30#note_32828466

@alterechtschreibung: Is removing "Alterechtschreibung" correct?

Edited by username-removed-124398