Fix AppImage build and launch

Use an older version of linuxdeploy to work around a FUSE memory
allocation error (see
https://discuss.pixls.us/t/countdown-to-5-12/49160/6).

Override the minimum CMake version when building libjxl to fix the CMake
configuration error for the sjpeg dependency.

.github/workflows/appimage.yml

@@ -157,7 +157,8 @@ jobs:
         working-directory: ./build
         run: |
           echo "Downloading linuxdeploy."
-          curl --location 'https://github.com/linuxdeploy/linuxdeploy/releases/download/continuous/linuxdeploy-x86_64.AppImage' > linuxdeploy-x86_64.AppImage
+          LINUXDEPLOY_TAG='1-alpha-20240109-1'
+          curl --location "https://github.com/linuxdeploy/linuxdeploy/releases/download/${LINUXDEPLOY_TAG}/linuxdeploy-x86_64.AppImage" > linuxdeploy-x86_64.AppImage
           echo "Downloading GTK plugin for linuxdeploy."
           curl --location 'https://raw.githubusercontent.com/linuxdeploy/linuxdeploy-plugin-gtk/master/linuxdeploy-plugin-gtk.sh' \
             | sed 's/^\(export GTK_THEME\)/#\1/' \

tools/makedeb/PKGBUILD.libjxl

@@ -25,6 +25,7 @@ build() {
   local _cmake_options=(
     -B build
     -S "$_pkgsrc"
+    -DCMAKE_POLICY_VERSION_MINIMUM=3.5
     -DCMAKE_BUILD_TYPE=Release
     -DCMAKE_INSTALL_PREFIX='/usr'
     -DJPEGXL_FORCE_SYSTEM_BROTLI=ON