I claim the ornamental design for a tourniquet, as shown and described.
FIG. 1 is a top perspective view of a tourniquet;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is an enlarged first end view thereof;
FIG. 4 is an enlarged second end view thereof;
FIG. 5 is a side elevational view thereof, the opposite side view being a mirror image;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The tourniquet is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design. The broken line showing of details in FIGS. 2 and 7 is included for the purpose of showing environmental portions of the design. No claim is made to the portions shown in broken line.