In triangle $XYZ$, angle $Y$ is a right angle, point $P$ lies on $\overline{XZ}$, and point $Q$ lies on $\overline{YZ}$ such that $\overline{PQ}$ is parallel to $\overline{XY}$. If the measure of angle $XZY$ is $63^{\circ }$, what is the measure, in degrees, of angle $XPQ$ ?