ProjectExplorer: Fix crash when renaming files

*Obviously*, the lambda captured a QStringBuilder object.

Change-Id: I585f7a9145b167265de20a720564bdc54b410be6
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/projectexplorer/projectexplorer.cpp

@@ -2547,7 +2547,8 @@ FilePairs ProjectExplorerPlugin::renameFiles(
                         "be updated accordingly: %1")
                     .arg(pathsAsHtmlList(renamedOnly));
         }
-        QTimer::singleShot(0, m_instance, [message = failedRenamingsString + renamedOnlyString] {
+        QTimer::singleShot(
+                    0, m_instance, [message = QString(failedRenamingsString + renamedOnlyString)] {
             QMessageBox::warning(
                         ICore::dialogParent(), Tr::tr("Renaming Did Not Fully Succeed"), message);
         });