I claim the ornamental design for music standza, as shown.
FIG. 1 is a perspective view of a music standza;
FIG. 2 is a front elevation view of a music standza;
FIG. 3 is a left side view of a music standza;
FIG. 4 is a right side view of a music standza;
FIG. 5 is a top view of a music standza;
FIG. 6 is a rear view of a music standza;
FIG. 7 is a bottom view of a music standza; and,
FIG. 8 is a perspective view of a music standza with the music display holder in an open position.
The broken-line disclosure is understood to represent portions of the article in which the claimed design is embodied, but which form no part of the claimed design.