The ornamental design for a T-wrench, as shown and described.
FIG. 1 is a perspective view of an T-wrench, showing our new design;
FIG. 2 is a left view thereof;
FIG. 3 is a right view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a back view thereof;
FIG. 6 is a bottom view thereof; and,
FIG. 7 is a top view thereof.
Those portions of the figures shown in dotted lines form no part of my invention, but are included to show the context and environment of the invention.