QPermission: add missing \since 6.5

The Q<Typed>Permission classes get their \since via \include
permissions.qdocinc permission-metadata, but using that for
QPermission will break the \annotatedlist permissions trick used all
over the permission docs, because QPermission would then be included
in the list. The use of this mechanism needs more thought; QPermission
shouldn't really be excluded from being \ingroup permissions.

Change-Id: I33207ffb39c04c23fb479c173e97dc0adb60691f
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
(cherry picked from commit 49cdfb0c61521f843046e473d759149ab4878ce3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/kernel/qpermissions.cpp

@@ -174,6 +174,7 @@ Q_LOGGING_CATEGORY(lcPermissions, "qt.permissions", QtWarningMsg);
     \class QPermission
     \inmodule QtCore
     \inheaderfile QPermissions
+    \since 6.5
     \brief An opaque wrapper of a typed permission.
 
     The QPermission class is an opaque wrapper of a \l{typed permission},