[staging-next] python312Packages.babelfont: add missing dependency (#379035)

pkgs/development/python-modules/babelfont/default.nix

···
   setuptools,
   setuptools-scm,
   ufolib2,
+  ufomerge,
   vfblib,
 }:
 
···
     openstep-plist
     orjson
     ufolib2
+    ufomerge
     vfblib
   ];