Update references (#1609)

Author: dweindl

doc/using_pypesto.bib

@@ -469,4 +469,19 @@ @Article{ErnstBan2025
   publisher        = {Springer Science and Business Media LLC},
 }
 
+@Article{PhilippsSch2025,
+  author           = {Philipps, Maren and Schmid, Nina and Hasenauer, Jan},
+  journal          = {npj Systems Biology and Applications},
+  title            = {Current state and open problems in universal differential equations for systems biology},
+  year             = {2025},
+  issn             = {2056-7189},
+  month            = aug,
+  number           = {1},
+  volume           = {11},
+  creationdate     = {2025-09-23T19:56:41},
+  doi              = {10.1038/s41540-025-00550-w},
+  modificationdate = {2025-09-23T19:56:41},
+  publisher        = {Springer Science and Business Media LLC},
+}
+
 @Comment{jabref-meta: databaseType:bibtex;}