Keep screenshot preview within a reasonable size when drag and drop is initiated

BUG: 443564

When one takes a screenshot with one side (either height or width) being around
five times bigger than the other size and initiating drag and drop, the preview
within the drag becomes comically huge.

src/SpectacleCore.cpp

@@ -522,7 +522,7 @@ void SpectacleCore::doStartDragAndDrop()
 
     auto lDragHandler = new QDrag(this);
     lDragHandler->setMimeData(lMimeData);
-    lDragHandler->setPixmap(lExportManager->pixmap().scaled(256, 256, Qt::KeepAspectRatioByExpanding, Qt::SmoothTransformation));
+    lDragHandler->setPixmap(lExportManager->pixmap().scaled(256, 256, Qt::KeepAspectRatio, Qt::SmoothTransformation));
     lDragHandler->exec(Qt::CopyAction);
 }