Fixed the fullscreen keyboard shortcut

`Qt::Key_F11` and `QKeySequence::FullScreen` are of different enum types
(`Qt::Key` and `QKeySequence::StandardKey`, respectively) with
overlapping value ranges. Using a standard integral type (int, unsigned,
long, etc) as a common type for them results in the type information
being lost and an ensuing impossibility to take advantage of overloaded
constructors of `QKeySequence`. The simple fix is to use `QKeySequence`
as the common type of the conditional expression.

src/kiwixapp.cpp

@@ -446,8 +446,8 @@ void KiwixApp::createActions()
             this, [=]() { getTabWidget()->openFindInPageBar(); });
 
     const auto fullScreenKeySeq = QKeySequence(QKeySequence::FullScreen).isEmpty()
-                                ? (int) Qt::Key_F11
-                                : (int) QKeySequence::FullScreen;
+                                ? QKeySequence(Qt::Key_F11)
+                                : QKeySequence(QKeySequence::FullScreen);
     CREATE_ACTION_ICON_SHORTCUT(ToggleFullscreenAction, "full-screen-enter", gt("set-fullscreen"), fullScreenKeySeq);
     connect(mpa_actions[ToggleFullscreenAction], &QAction::toggled,
             this, [=](bool checked) {