CMakeLists: just search for the wayland-scanner binary

[andresilva]

Otherwise after NixOS/nixpkgs#214906 you get:

xdg-desktop-portal-hyprland> CMake Error in CMakeLists.txt:
xdg-desktop-portal-hyprland>   Imported target "PkgConfig::deps" includes non-existent path
xdg-desktop-portal-hyprland>     "/nix/store/0ikl83z4h69imxkwsly3hcm424f7wi7j-wayland-scanner-1.23.0-dev/include"
xdg-desktop-portal-hyprland>   in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:
xdg-desktop-portal-hyprland>   * The path was deleted, renamed, or moved to another location.
xdg-desktop-portal-hyprland>   * An install or uninstall procedure did not complete successfully.
xdg-desktop-portal-hyprland>   * The installation package was faulty and references files it does not
xdg-desktop-portal-hyprland>   provide.

[fufexan]

Oh shit didn't see this and already pushed a commit for it.

[fufexan]

Still, nicer handling than my commit. LGTM.