QmlDesigner: Add missing stream read

Change-Id: I5a93a6ef37b9f0608e82b2b9d4453f792b813da1
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

share/qtcreator/qml/qmlpuppet/container/imagecontainer.cpp

@@ -225,6 +225,7 @@ static void readStream(QDataStream &in, ImageContainer &container)
     in >> imageSize;
     in >> imageFormat;
     in >> byteCount;
+    in >> pixelRatio;
 
     QImage image = QImage(imageSize, QImage::Format(imageFormat));