Use QWidget::screen() to fix compile with Qt 5.14

src/ui/albumcoverchoicecontroller.cpp

@@ -247,7 +247,7 @@ QDialog* AlbumCoverChoiceController::ShowCoverPrivate(const Song& song) {
   // if the cover is larger than the screen, resize the window
   // 85% seems to be enough to account for title bar and taskbar etc.
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
-  QScreen* screen = screen();
+  QScreen* screen = QWidget::screen();
 #else
   QScreen* screen =
       (window() && window()->windowHandle() ? window()->windowHandle()->screen()

src/ui/settingsdialog.cpp

@@ -306,7 +306,7 @@ void SettingsDialog::showEvent(QShowEvent* e) {
 
   // Resize the dialog if it's too big
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
-  QScreen* screen = screen();
+  QScreen* screen = QWidget::screen();
 #else
   QScreen* screen =
       (window() && window()->windowHandle() ? window()->windowHandle()->screen()

src/widgets/nowplayingwidget.cpp

@@ -650,7 +650,7 @@ void NowPlayingWidget::SearchCoverAutomatically() {
 
 void NowPlayingWidget::Bask() {
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
-  QScreen* screen = screen();
+  QScreen* screen = QWidget::screen();
 #else
   QScreen* screen =
       (window() && window()->windowHandle() ? window()->windowHandle()->screen()

src/widgets/prettyimage.cpp

@@ -198,7 +198,7 @@ void PrettyImage::ShowFullsize() {
 
   // Work out how large to make the window, based on the size of the screen
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
-  QScreen* screen = screen();
+  QScreen* screen = QWidget::screen();
 #else
   QScreen* screen =
       (window() && window()->windowHandle() ? window()->windowHandle()->screen()