According to the most recent standard, the notation of the packages have a rectangular title field (see https://www.omg.org/spec/UML/2.5.1/PDF chapter 12.2.4 Notation) instead of the currently generated trapezoid title field.
Is it possible to draw packages like in the standard? It would be nice if you could add this functionality (either as a new "skinparam PackageStyle" value or part of the "strictuml" setting).