Return a shrunk fitz.Rect for given wx.Rect.

def wxRect_to_Rect(self, wr):
        """ Return a shrunk fitz.Rect for given wx.Rect."""
        r = fitz.Rect(wr.x, wr.y, wr.x + wr.width, wr.y + wr.height)
        return r * self.shrink