Compile with getOpenGileContent() API changes

getOpenGileContent() takes a parent now, and the compat
API is behind a QT_WIDGETS_REMOVED_SINCE(6, 7) which
the manual tests can't access.

Pick-to: 6.7
Change-Id: I81784baed178bb8efd1a848d32c9ee4510971e26
Reviewed-by: Piotr Wierciński <piotr.wiercinski@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

tests/manual/wasm/localfiles/main.cpp

@@ -91,7 +91,8 @@ private Q_SLOTS:
     {
         QFileDialog::getOpenFileContent(
             m_filterEdit->text(),
-            std::bind(&AppWindow::onFileContentReady, this, std::placeholders::_1, std::placeholders::_2));
+            std::bind(&AppWindow::onFileContentReady, this, std::placeholders::_1, std::placeholders::_2),
+            &m_loadFileUi);
     }
 
     void onSaveClicked()