Fix Linux CI

Author: Jmgr

.github/workflows/linux.yml

@@ -20,7 +20,7 @@ jobs:
     - name: Install Qt
       uses: jurplel/install-qt-action@v4
       with:
-        version: 6.8.3
+        version: 6.4.3
         arch: gcc_64
         modules: 'qtspeech qtmultimedia qt5compat'
         dir: ${{ github.workspace }}/Qt