Change from service to application so GPU temperature works

Service/SystemTemperatureService.cs

@@ -1,6 +1,7 @@
 using OpenHardwareMonitor.Hardware;
 using System.Collections.Generic;
 using System.Linq;
+using System.Windows;
 
 namespace SystemTemperatureService
 {
@@ -56,5 +57,10 @@ namespace SystemTemperatureService
 
             return deviceList;
         }
+
+        public void Shutdown()
+        {
+            Program.MainDispatcher.Invoke(Application.Current.Shutdown);
+        }
     }
 }