openmodelica: mark as broken, unmaintained

(cherry picked from commit d9298e3a00edc796b040373a64a6284f60813278)

pkgs/applications/science/misc/openmodelica/default.nix

···
     license     = licenses.gpl3;
     maintainers = with maintainers; [ smironov ];
     platforms   = platforms.linux;
+    broken      = true;
   };
 }