replace qAsConst with std::as_const in nglpdfdocument

Reduce Qt deprecation warnings

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Z/src/nglwidgets/nglpdfdocument.cpp

@@ -163,7 +163,7 @@ void PDFDocument::setZoomFactor(double zoom)
     return;
   m_scaleFactor = zoom;
   
-  for (PDFPage *p : qAsConst(m_pages))
+  for (PDFPage *p : std::as_const(m_pages))
     p->setZoomFactor(m_scaleFactor / m_widthFactor);
 
   rebuildRanges();
@@ -177,7 +177,7 @@ void PDFDocument::setRotation(Poppler::Page::Rotation rot)
   if (m_pages.isEmpty())  
     return;
   
-  for (PDFPage *p : qAsConst(m_pages))
+  for (PDFPage *p : std::as_const(m_pages))
     p->setRotation(m_rotation);
 
   rebuildRanges();
@@ -322,7 +322,7 @@ void PDFDocument::rebuildRanges()
   QVBoxLayout *l = qobject_cast<QVBoxLayout *> (m_pdfLabel->layout());
   m_ranges.clear();
   int height = l->contentsMargins().top();
-  for (PDFPage *p : qAsConst(m_pages))
+  for (PDFPage *p : std::as_const(m_pages))
   {
     m_ranges += height;
     height += p->height();