fix: fix slot connect fail log when running app

- fix slot connect fail log when running app
- fix potential memory leak

app/actionmanager.h

@@ -22,7 +22,6 @@ public:
     void setupAction(MainWindow * mainWindow);
     void setupShortcuts();
 
-public slots:
     void updateActionState(PlaylistManager* pm, GraphicsView* gv);
 
 public:

app/mainwindow.cpp

@@ -180,6 +180,7 @@ MainWindow::MainWindow(QWidget *parent)
 
 MainWindow::~MainWindow()
 {
+    delete m_am;
     delete ui;
 }