fix(sessionmanager): adapt QString::arg usage for Qt 6.10

Qt 6 no longer accepts QDBusReply<T> as an argument to QString::arg().
Passing a QDBusReply<unsigned int> directly results in a template
substitution failure with enable_if<false>.

This fix extracts the actual value using .value() before passing it
to QString::arg(), restoring compatibility with Qt 6.10 and preserving
existing logic.

Author: hillwoodroc

src/dde-session/impl/sessionmanager.cpp

@@ -484,7 +484,8 @@ void SessionManager::RequestSuspend()
 void SessionManager::SetLocked(bool lock)
 {
     // 仅允许dde-lock进程调用
-    QString cmdLine = QString("/proc/%1/cmdline").arg(connection().interface()->servicePid(message().service()));
+    QString cmdLine = QString("/proc/%1/cmdline").arg(connection().interface()->servicePid(message().service()).value());
+    
     QFile file(cmdLine);
 
     // NOTE: 如果以deepin-turbo进行加速启动，这里是不准确的，可能需要判断desktop文件的全路径，不过deepin-turbo后续应该会放弃支持