In KF6 it's simply exposed as Kirigami
Fixes the CMake warning:
CMake Warning (dev) at /home/isma/kde/usr/lib/x86_64-linux-gnu/cmake/KF6Kirigami2/KF6Kirigami2Config.cmake:28 (message): find_package(KF6Kirigami2) is deprecated, use find_package(KF6Kirigami) instead