The ornamental design for a pinnailer, as shown and described.
FIG. 1 is a left perspective view of a pin nailer showing my new design;
FIG. 2 is a right perspective view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a front view thereof; and,
FIG. 8 is a rear view thereof.
The broken line showing of structural features is included for the purpose of illustrating non-claimed subject matter and forms no part of the claimed design.