add missing curly brace so docs build

Author: louisfh

src/bibtex/all.bib

@@ -1867,6 +1867,7 @@ @article{Magnusson+etal:2024:posteriordb
   author={Magnusson, M{\aa}ns and Torgander, Jakob and B{\"u}rkner, Paul-Christian and Zhang, Lu and Carpenter, Bob and Vehtari, Aki},
   journal={arXiv preprint arXiv:2407.04967},
   year={2024}
+}
 
 @article{egozcue+etal:2003,
   title={Isometric logratio transformations for compositional data analysis},