The ornamental design for a scooter, as shown and described.
1. Scooter
Reproduction 1.1 is a top view of the subject design; Reproduction 1.2 is a right view of the subject design; Reproduction 1.3 is a front view of the subject design; Reproduction 1.4 is back view of the subject design; Reproduction 1.5 is a perspective view of the subject design; Reproduction 1.6 is another perspective view of the subject design.