ci: Switch to Qt 6.8

(cherry picked from commit 637b30f313)

Co-authored-by: Vlad Zahorodnii <vlad.zahorodnii@kde.org>

.gitlab-ci.yml

@@ -7,8 +7,8 @@ include:
       - /gitlab-templates/linux-qt6.yml
       - /gitlab-templates/freebsd-qt6.yml
 
-suse_tumbleweed_qt67_reduced_featureset:
+suse_tumbleweed_qt68_reduced_featureset:
-    extends: suse_tumbleweed_qt67
+    extends: suse_tumbleweed_qt68
     script:
     - git config --global --add safe.directory $CI_PROJECT_DIR
     - python3 -u ci-utilities/run-ci-build.py --project $CI_PROJECT_NAME --branch $CI_COMMIT_REF_NAME --platform Linux --extra-cmake-args="-DKWIN_BUILD_KCMS=OFF -DKWIN_BUILD_SCREENLOCKER=OFF -DKWIN_BUILD_TABBOX=OFF -DKWIN_BUILD_ACTIVITIES=OFF -DKWIN_BUILD_RUNNERS=OFF -DKWIN_BUILD_NOTIFICATIONS=OFF -DKWIN_BUILD_GLOBALSHORTCUTS=OFF -DKWIN_BUILD_X11=OFF -DKWIN_BUILD_EIS=OFF" --skip-publishing