TouchHandler: remove unused FreeRTOS.h and task.h includes from header

FreeRTOS and task.h aren't used in the Header file. Furthermore the
SystemTask forward declaration isn't needed as it isn't used in the
header.

src/touchhandler/TouchHandler.h

@@ -1,8 +1,6 @@
 #pragma once
 #include "drivers/Cst816s.h"
 #include "systemtask/SystemTask.h"
-#include <FreeRTOS.h>
-#include <task.h>
 
 namespace Pinetime {
   namespace Components {
@@ -11,9 +9,6 @@ namespace Pinetime {
   namespace Drivers {
     class Cst816S;
   }
-  namespace System {
-    class SystemTask;
-  }
   namespace Controllers {
     class TouchHandler {
       public: