FIX: t_utc parse overflow

Change-Id: If0358a8458fcd9a79f61b6efe5b4720c5682dccc
Jira: none
(cherry picked from commit f6672805a2d990a77192b14db199e6ff96956bb7)

src/slic3r/GUI/DeviceManager.cpp

@@ -2714,7 +2714,7 @@ int MachineObject::parse_json(std::string payload)
             j = j_pre;
         }
 
-        uint64_t t_utc = j.value("t_utc", 0);
+        uint64_t t_utc = j.value("t_utc", 0ULL);
         if (t_utc > 0) 
             last_update_time = std::chrono::system_clock::time_point(t_utc * 1ms);