Drop Qt 5 support

Qt 6 has been available for almost 4 years. Qt 5 is no longer officially supported by Qt for opensource, it's time to drop Qt 5.

src/analyzer/analyzercontainer.cpp

@@ -116,11 +116,7 @@ void AnalyzerContainer::mouseReleaseEvent(QMouseEvent *e) {
   }
 
   if (e->button() == Qt::RightButton) {
-#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
     context_menu_->popup(e->globalPosition().toPoint());
-#else
-    context_menu_->popup(e->globalPos());
-#endif
   }
 
 }