simple fix to remove the segfault with Qt>=6.7 (CGAL#8453)

## Summary of Changes

This should fix CGAL#8232. I have tested locally. I hope that does not 


## Release Management

* Affected package(s): GraphicsView, Qt6
* Issue(s) solved (if any): fix CGAL#8232
* License and copyright ownership: bug fix

GraphicsView/include/CGAL/Qt/qglviewer_impl.h

@@ -354,7 +354,6 @@ camera is manipulated) : main drawing method. Should be overloaded. \arg
 postDraw() : display of visual hints (world axis, FPS...) */
 CGAL_INLINE_FUNCTION
 void CGAL::QGLViewer::paintGL() {
-  makeCurrent();
   // Clears screen, set model view matrix...
   preDraw();
   // Used defined method. Default calls draw()
@@ -364,7 +363,6 @@ void CGAL::QGLViewer::paintGL() {
     draw();
   // Add visual hints: axis, camera, grid...
   postDraw();
-  doneCurrent();
   Q_EMIT drawFinished(true);
 }