Silence warning about deliberately using deprecated API

We test moc's support for [[deprecated]], so don't warn about it.

Pick-to: 6.5
Change-Id: Ifda2b81c14cb9802db4bb1d0a1eb17d978ad492a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

tests/auto/tools/moc/tst_moc.cpp

@@ -4026,7 +4026,9 @@ void tst_Moc::cxx17Namespaces()
 
 void tst_Moc::cxxAttributes()
 {
+QT_WARNING_PUSH QT_WARNING_DISABLE_DEPRECATED
     auto so = CppAttribute::staticMetaObject;
+QT_WARNING_POP
     QCOMPARE(so.className(), "CppAttribute");
     QCOMPARE(so.enumeratorCount(), 0);
     QVERIFY(so.indexOfSignal("deprecatedSignal") != 1);