After updating the portage tree I got the following problem:

!!! The following update has been skipped due to unsatisfied dependencies:

dev-python/PyQt5:0

 selected: (dev-python/PyQt5-5.10.1-r1:0/0::python-modules-kit, installed)
 skipped: (dev-python/PyQt5-5.11.3:0/0::python-modules-kit, ebuild scheduled for merge) (see unsatisfied dependency below)

emerge: there are no ebuilds to satisfy ">=dev-qt/qtcore-5.9.6:5".
(dependency required by "dev-python/PyQt5-5.11.3::python-modules-kit" [ebuild])