fix: update DOI in paper metadata and remove unnecessary affiliation

Author: FabrizioMusacchio

paper/paper.md

@@ -36,7 +36,7 @@ authors:
     affiliation: 1
   - name: Felix Christopher Nebeling
     orcid: 0000-0002-2749-7163
-    affiliation: [1]
+    affiliation: 1
   - name: Katharina Wolff
     orcid: 0009-0009-9180-3549
     affiliation: 1