shell build without systemd support breaks by missing libsystemd though systemd support is not enabled

I saw [this issue](https://github.com/lirios/shell/issues/225)

i am on artix linux openrc and try to build liri-shell-git from aur.

`-DFEATURE_enable_systemd:BOOL=OFF` is added to `cmake`.

Here the output:
```
-- The following features have been disabled:

* Coverage, Code coverage (gcc only)
* Liri::DevelopmentBuild, Build Liri Shell for development
* Liri::Systemd, Enable systemd support
* Shell::QtQuickCompiler, Build with QtQuick compiler

-- Found Wayland: /usr/lib/libwayland-server.so (found suitable version "1.22.0", minimum required is "1.15") found components: Server
-- Found Wayland: /usr/lib/libwayland-client.so (found suitable version "1.22.0", minimum required is "1.15") found components: Client
-- Found Wayland: /usr/lib/libwayland-server.so (found suitable version "1.22.0", minimum required is "1.15") found components: Server
-- Adding Qt5::DBus target to MprisQmlPlugin
-- Found Wayland: /usr/lib/libwayland-client.so;/usr/lib/libwayland-server.so;/usr/lib/libwayland-cursor.so;/usr/lib/libwayland-egl.so (found version "1.22.0")
-- Found Wayland: /usr/lib/libwayland-client.so;/usr/lib/libwayland-server.so;/usr/lib/libwayland-cursor.so;/usr/lib/libwayland-egl.so (found suitable version "1.22.0", minimum required is "1.15") found components: Server
-- Found Wayland: /usr/lib/libwayland-client.so (found suitable version "1.22.0", minimum required is "1.15") found components: Client
-- Configuring done (0.2s)
CMake Error at /usr/share/LiriCMakeShared/modules/LiriBuild.cmake:189 (target_link_libraries):
Target "LiriShellHelper" links to:

PkgConfig::Libsystemd

but the target was not found. Possible reasons include:

* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.

Call Stack (most recent call first):
src/helper/CMakeLists.txt:48 (liri_extend_target)

CMake Error at /usr/share/LiriCMakeShared/modules/LiriBuild.cmake:189 (target_link_libraries):
Target "LiriShellLockscreen" links to:

PkgConfig::Libsystemd

but the target was not found. Possible reasons include:

* There is a typo in the target name.
* A find_package call is missing for an IMPORTED target.
* An ALIAS target is missing.

Call Stack (most recent call first):
src/lockscreen/CMakeLists.txt:49 (liri_extend_target)

-- Generating done (0.0s)
CMake Generate step failed. Build files cannot be regenerated correctly.
```
What can i do?