Let the point \( P \) be the vertex of the parabola \( y = x^{2} - 6x + 12 \). If a line passing through the point \( P \) intersects the circle \( x^{2} + y^{2} - 2x - 4y + 3 = 0 \) at the point \( R \) and \( S \), then the maximum value of \( (PR + PS)^{2} \) is:
