The ornamental design for a carrier, as shown and described.
FIG. 1 is a top plan view of the carrier, showing my new design;
FIG. 2 is a bottom plan view thereof;
FIG. 3 is a top plan view thereof, where the carrier has been folded in half; and,
FIG. 4 is a left side elevation view thereof; the right side being a mirror image view thereof.
The circularly arranged broken lines in the center of the carrier depict a button clasp and do not form a part of the claim. The longer dashed lines near the interior and exterior edges of the article depict stitching.