QXmlStreamWriter: remove unused [[maybe_unused]]

Q_ASSERT() already ensures its argument gets compiled even with
QT_NO_DEBUG, but then skipped as dead code.

Task-number: QTBUG-103302
Change-Id: I6614b23967e2bb506e52f1493526564a0b5955be
Reviewed-by: Mate Barany <mate.barany@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/corelib/serialization/qxmlstream.cpp

@@ -64,21 +64,18 @@ auto transform(QUtf8StringView haystack, char needle)
     return R{haystack, needle};
 }
 
-[[maybe_unused]]
 auto transform(QLatin1StringView haystack, QLatin1StringView needle)
 {
     struct R { QLatin1StringView haystack; QLatin1StringView needle; };
     return R{haystack, needle};
 }
 
-[[maybe_unused]]
 auto transform(QStringView haystack, QLatin1StringView needle)
 {
     struct R { QStringView haystack; QLatin1StringView needle; };
     return R{haystack, needle};
 }
 
-[[maybe_unused]]
 auto transform(QUtf8StringView haystack, QLatin1StringView needle)
 {
     struct R { QLatin1StringView haystack; QLatin1StringView needle; };