The ornamental design for an article of footwear, as shown and described.
FIG. 1 is a top perspective view of an article of footwear showing our new design.
FIG. 2 is a front view thereof.
FIG. 3 is a rear view thereof.
FIG. 4 is a left side view thereof.
FIG. 5 is a right side view thereof.
FIG. 6 is a top view thereof.
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a cross-sectional view taken along line 8-8 of FIG. 6.
The broken lines showing the remaining portions of the article of footwear illustrate features of the article of manufacture that form no part of the claimed design.
The hatching shown in FIG. 8 is symbolic and forms no part of the claimed design.