Drop Qt 5 support

Qt 6 has been available for almost 4 years. Qt 5 is no longer officially supported by Qt for opensource, it's time to drop Qt 5.

src/covermanager/albumcoverchoicecontroller.cpp

@@ -507,11 +507,7 @@ void AlbumCoverChoiceController::ShowCover(const Song &song, const QPixmap &pixm
   }
 
   dialog->setWindowTitle(title_text);
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 15, 0))
   dialog->setFixedSize(label->pixmap(Qt::ReturnByValue).size() / pixmap.devicePixelRatioF());
-#else
-  dialog->setFixedSize(label->pixmap()->size() / pixmap.devicePixelRatioF());
-#endif
   dialog->show();
 
 }
@@ -721,11 +717,7 @@ void AlbumCoverChoiceController::SaveCoverEmbeddedToCollectionSongs(const Song &
 
 void AlbumCoverChoiceController::SaveCoverEmbeddedToCollectionSongs(const QString &effective_albumartist, const QString &effective_album, const QString &cover_filename, const QByteArray &image_data, const QString &mime_type) {
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
   QFuture<SongList> future = QtConcurrent::run(&CollectionBackend::GetAlbumSongs, app_->collection_backend(), effective_albumartist, effective_album, CollectionFilterOptions());
-#else
-  QFuture<SongList> future = QtConcurrent::run(&*app_->collection_backend(), &CollectionBackend::GetAlbumSongs, effective_albumartist, effective_album, CollectionFilterOptions());
-#endif
   QFutureWatcher<SongList> *watcher = new QFutureWatcher<SongList>();
   QObject::connect(watcher, &QFutureWatcher<SongList>::finished, this, [this, watcher, cover_filename, image_data, mime_type]() {
     const SongList collection_songs = watcher->result();

src/covermanager/albumcoverloader.cpp

@@ -408,11 +408,7 @@ void AlbumCoverLoader::LoadRemoteImageFinished(QNetworkReply *reply, TaskPtr tas
   reply->deleteLater();
 
   QVariant redirect = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
   if (redirect.isValid() && redirect.metaType().id() == QMetaType::QUrl) {
-#else
-  if (redirect.isValid() && redirect.type() == QVariant::Url) {
-#endif
     if (task->redirects++ >= kMaxRedirects) {
       ProcessTask(task);
       return;

src/covermanager/albumcovermanager.cpp

@@ -319,11 +319,7 @@ void AlbumCoverManager::SaveSettings() {
 
 void AlbumCoverManager::CancelRequests() {
 
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
   app_->album_cover_loader()->CancelTasks(QSet<quint64>(cover_loading_tasks_.keyBegin(), cover_loading_tasks_.keyEnd()));
-#else
-  app_->album_cover_loader()->CancelTasks(QSet<quint64>::fromList(cover_loading_tasks_.keys()));
-#endif
   cover_loading_pending_.clear();
   cover_loading_tasks_.clear();
   cover_save_tasks_.clear();

src/covermanager/albumcovermanagerlist.cpp

@@ -42,11 +42,7 @@
 
 AlbumCoverManagerList::AlbumCoverManagerList(QWidget *parent) : QListWidget(parent), manager_(nullptr) {}
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 QMimeData *AlbumCoverManagerList::mimeData(const QList<QListWidgetItem*> &items) const {
-#else
-QMimeData *AlbumCoverManagerList::mimeData(const QList<QListWidgetItem*> items) const {
-#endif
 
   // Get songs
   SongList songs;

src/covermanager/albumcovermanagerlist.h

@@ -44,11 +44,7 @@ class AlbumCoverManagerList : public QListWidget {
   void set_cover_manager(AlbumCoverManager *manager) { manager_ = manager; }
 
  protected:
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
   QMimeData *mimeData(const QList<QListWidgetItem*> &items) const override;
-#else
-  QMimeData *mimeData(const QList<QListWidgetItem*> items) const override;
-#endif
 
   void dropEvent(QDropEvent*) override {}