Added guards for colorSchemechanged and Qt::ColorScheme. updated workflow to save apt cache

.github/workflows/release-nearby-qml-tray.yaml

@@ -33,6 +33,14 @@ jobs:
           # Share repository cache between workflows.
           repository-cache: true
 
+      - name: Cache apt packages
+        uses: actions/cache@v4
+        with:
+          path: /var/cache/apt/archives
+          key: apt-${{ runner.os }}-${{ hashFiles('.github/workflows/release-nearby-qml-tray.yaml') }}
+          restore-keys: apt-${{ runner.os }}-
+          save-always: true
+
       - name: Install Linux build dependencies
         run: |
           sudo apt-get update

sharing/linux/qml_tray_app/file_share_tray_main.cpp

@@ -155,10 +155,12 @@ int main(int argc, char* argv[]) {
 
   QObject::connect(&app, &QCoreApplication::aboutToQuit, &controller,
                    [&controller]() { controller.stop(); });
+#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
   QObject::connect(app.styleHints(), &QStyleHints::colorSchemeChanged, &tray,
                    [&tray, &resolve_tray_icon](Qt::ColorScheme) {
                      tray.setIcon(resolve_tray_icon());
                    });
+#endif
 
   tray.setContextMenu(&tray_menu);
   tray.show();