Fix implicit int -> float conversion deprecation warnings

gui/application.py:350: DeprecationWarning: an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
  window.setX(size.width() / 2 - window.minimumWidth() / 2)

gui/application.py:747: DeprecationWarning: an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
  self.systray_window.setX(pos_x)

updater/base.py:356 an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
  self.updateProgress.emit(self.progress)