ci: reuse the runner CMake to avoid slow redundant downloads

Author: MCDFsteve

scripts/install_linux_dependencies.sh

@@ -2,7 +2,12 @@
 # Bern needs DBus; the desktop engine's native file picker needs Wayland.
 set -euo pipefail
 
-packages=(build-essential pkg-config cmake libdbus-1-dev libwayland-dev)
+packages=(build-essential pkg-config libdbus-1-dev libwayland-dev)
+# GitHub's image already supplies CMake outside dpkg. Downloading the distro
+# copy again adds an unnecessary large mirror fetch to every quality/build job.
+if ! cmake --version >/dev/null 2>&1; then
+  packages+=(cmake)
+fi
 case "${1:-core}" in
   core) ;;
   gtk) packages+=(libgtk-4-dev libadwaita-1-dev libwebkitgtk-6.0-dev) ;;
@@ -22,6 +27,7 @@ sudo env DEBIAN_FRONTEND=noninteractive NEEDRESTART_MODE=a \
   apt-get "${apt_options[@]}" -o Dpkg::Options::=--force-confdef \
   -o Dpkg::Options::=--force-confold install -y --no-install-recommends "${packages[@]}"
 pkg-config --modversion dbus-1 wayland-client
+cmake --version
 if [[ "${1:-core}" == gtk ]]; then
   pkg-config --modversion gtk4 libadwaita-1 webkitgtk-6.0
 fi