Update Year in Licenses
This updates "2019 Forschungszentrum" to "2017-2020 Forschungszentrum", because we have 2020 by now.
For later reference, this was the shell one-liner:
rg "2019 Forschungszentrum" --files-with-matches | xargs gsed -i "s/2019 Forschungszentrum/2017-2020 Forschungszentrum/"