refactor: fix deprecation up to Qt 5.15

Signed-off-by: Sefa Eyeoglu <contact@scrumplex.net>

launcher/LoggedProcess.cpp

@@ -157,19 +157,6 @@ void LoggedProcess::on_stateChange(QProcess::ProcessState state)
     }
 }
 
-#if defined Q_OS_WIN32
-#include <windows.h>
-#endif
-
-qint64 LoggedProcess::processId() const
-{
-#ifdef Q_OS_WIN
-    return pid() ? pid()->dwProcessId : 0;
-#else
-    return pid();
-#endif
-}
-
 void LoggedProcess::setDetachable(bool detachable)
 {
     m_is_detachable = detachable;