fix: grab rect dpi error on linux

QtScrcpy/device/ui/videoform.cpp

@@ -109,8 +109,8 @@ QRect VideoForm::getGrabCursorRect()
 #elif defined(Q_OS_LINUX)
     rc = QRect(ui->keepRatioWidget->mapToGlobal(m_videoWidget->pos()), m_videoWidget->size());
     // high dpi support -- taken from the WIN32 section and untested
-    rc.setTopLeft(rc.topLeft() * m_videoWidget->devicePixelRatio());
-    rc.setBottomRight(rc.bottomRight() * m_videoWidget->devicePixelRatio());
+    rc.setTopLeft(rc.topLeft() * m_videoWidget->devicePixelRatioF());
+    rc.setBottomRight(rc.bottomRight() * m_videoWidget->devicePixelRatioF());
 
     rc.setX(rc.x() + 10);
     rc.setY(rc.y() + 10);