refactor: update upload workflow to V4, run in correct mode

- artifact upload v3 will be deprecated on Dec 4th
- tics analyzer seems to have run in diagnostic mode, need to test in
  production (qserver/client) modes now

.github/workflows/coverage.yaml

@@ -63,7 +63,7 @@ jobs:
         uses: actions/configure-pages@v5
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
         with:
           path: coverage
 
@@ -92,8 +92,8 @@ jobs:
           # Use 'qserver' for push to main branch, 'client' for others. See:
           # https://github.com/tiobe/tics-github-action?tab=readme-ov-file#client-default
           # mode: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' && 'qserver' || 'client' }}
-          # mode: ${{ github.ref == 'refs/heads/main' && 'qserver' || 'client' }}
-          mode: diagnostic
+          mode: ${{ github.ref == 'refs/heads/main' && 'qserver' || 'client' }}
+          #mode: diagnostic
           project: maas-ui
           viewerUrl: https://canonical.tiobe.com/tiobeweb/TICS/api/cfg?name=default
           ticsAuthToken: ${{ secrets.TICSAUTHTOKEN }}