The ornamental design for a tool handle, as shown (and described).
FIG. 1 is a perspective view of a tool handle showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a right side view thereof; and,
FIG. 8 is a view showing the application thereof, wherein the broken line portion is for illustrative purpose only and forms no part of the claimed design.