removed unnecessary icon change

On clicking the stop button in project preview, after playing a media, the icon of play button was already getting changed through connected signal. So there was no need to change it again.

Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>

src/Gui/preview/PreviewWidget.cpp

@@ -190,7 +190,6 @@ PreviewWidget::stop()
     {
         m_previewStopped = true;
         m_renderer->stop();
-        m_ui->pushButtonPlay->setIcon( QIcon( ":/images/play" ) );
     }
 }