Replace QHoverEvent::pos() with position().toPoint()

[111/192] Building CXX object lib/CMakeFiles/gwenviewlib.dir/thumbnailview/thumbnailbarview.cpp.o
~/kde/src/gwenview/lib/thumbnailview/thumbnailbarview.cpp: In member function ‘bool Gwenview::ThumbnailBarItemDelegatePrivate::hoverEventFilter(QHoverEvent*)’:
~/kde/src/gwenview/lib/thumbnailview/thumbnailbarview.cpp:116:54: warning: ‘QPoint QHoverEvent::pos() const’ is deprecated: Use position() [-Wdeprecated-declarations]
  116 |         QModelIndex index = mView->indexAt(event->pos());
      |                                            ~~~~~~~~~~^~
In file included from ~/Qt/6.8.0/gcc_64/include/QtGui/QHelpEvent:1,
                 from ~/kde/src/gwenview/lib/thumbnailview/thumbnailbarview.cpp:27:
~/Qt/6.8.0/gcc_64/include/QtGui/qevent.h:262:19: note: declared here
  262 |     inline QPoint pos() const { return position().toPoint(); }
      |                   ^~~