Fix Warning about KF5::KSysGuard target being deprecated
Summary:
Warnings such as:
CMake Warning at /usr/lib/x86_64-linux-gnu/cmake/KF5SysGuard/KF5SysGuardConfig.cmake:37 (me ssage): The KF5:: namespace for KSysGuard targets is deprecated. Please use KSysGuard as namespace. Call Stack (most recent call first): /usr/share/ECM/find-modules/FindKF5.cmake:74 (find_package) CMakeLists.txt:55 (find_package)
Test Plan: cmake does not output those warnings
Reviewers: Plasma, ahiemstra, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D29623