Put back KIO in the package search

One of the plugins links against KIOWidgets, which means that CMake will
fail configuration if KIO is not found.
2 jobs for master in 6 minutes and 33 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #59689
build_clazy_clang_tidy

00:06:31

passed #59688
linux kf5-qt5 qt5.12

00:06:33

18.0%