Fastener

FIG. 1 is a top perspective view of a fastener, showing our new design; FIG. 2 is a bottom perspective view thereof; FIG. 3 is a front elevation view thereof; FIG. 4 is a rear elevation view thereof; FIG. 5 is a left elevation view thereof; FIG. 6 is a right elevation view thereof; FIG. 7 is a top plan view thereof; and, FIG. 8 is a bottom plan view thereof. The dash-dash broken lines are included for the purpose of illustrating environmental structures and form no part of the claimed design. The dot-dash broken lines define the bounds of the claimed design and form no part thereof.