CI Linux install libdecor Cairo plugin explicitly

Instead of ensuring that the plugin is present, instal the Cairo plugin
directly.

The Cairo implementation is the only libdecor plugin present in U22.04
repositories (U24.04 has the Gtk implementation as well).

Author: MartinPulec

.github/scripts/Linux/prepare.sh

@@ -25,8 +25,7 @@ sudo apt install appstream `# appstreamcli for mkappimage AppStream validation`
         asciidoc
 sudo apt install fonts-dejavu-core
 sudo apt --no-install-recommends install nvidia-cuda-toolkit
-sudo apt install libdecor-0-0 &&
- ls /usr/lib/x86_64-linux-gnu/libdecor/plugins-1/*so >/dev/null # check plugin
+sudo apt install libdecor-0-0 libdecor-0-plugin-1-cairo
 sudo apt install libglew-dev
 sudo apt install libglm-dev
 sudo apt install imagemagick libmagickwand-dev