Add Sven Nahnsen to preffered citation

Author: sven1103

CITATION.cff

@@ -41,6 +41,9 @@ preferred-citation:
     - family-names: Fillinger
       given-names: Sven
       orcid: "https://orcid.org/0000-0001-8835-2219"
+    - family-names: Nahnsen
+      given-names: Sven
+      orcid: https://orcid.org/0000-0002-4375-0691
   doi: 10.5281/zenodo.18327776
   year: 2026