ci: Save gnome-shell meson logs artifacts on failure

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3793>

.gitlab-ci.yml

@@ -610,6 +610,12 @@ can-run-gnome-shell@x86_64:
     - meson setup gnome-shell gnome-shell/build --prefix /usr -Dbuildtype=debugoptimized -Dman=false --werror --fatal-meson-warnings
     - sudo meson install -C gnome-shell/build
     - dbus-run-session -- xvfb-run meson test -C gnome-shell/build --no-rebuild --timeout-multiplier 5
+  artifacts:
+    expire_in: 7 day
+    name: "mutter-${CI_JOB_NAME}-${CI_COMMIT_REF_NAME}"
+    when: on_failure
+    paths:
+      - gnome-shell/build/meson-logs
 
 test-mutter-coverity:
   rules: