It's already in qt5.14

src/akregator_part.cpp

@@ -406,11 +406,7 @@ bool Part::writeToTextFile(const QString &data, const QString &filename) const
     QTextStream stream(&file);
     stream.setCodec("UTF-8");
     stream << data
-          #if (QT_VERSION < QT_VERSION_CHECK(5, 15, 0))
-        << endl
-          #else
         << Qt::endl
-          #endif
     ;
     return file.commit();
 }