Include <thread> for std::this_thread::sleep_for

Fixes the build with gcc11.

autotests/fakeserver/fakedevice.cpp

@@ -25,6 +25,7 @@
 #include <QDBusError>
 
 #include <chrono>
+#include <thread>
 
 using namespace std::chrono_literals;
 

autotests/fakeserver/fakemanager.cpp

@@ -29,6 +29,7 @@
 #include <QDebug>
 
 #include <chrono>
+#include <thread>
 
 using namespace std::chrono_literals;