Swing seat

The design is the visual features of the SWING SEAT shown in the drawings, whether those features are features of one of shape, configuration, ornament or pattern or are a combination of any of those features. The portions shown in stippled lines do not form part of the design. Figure 1 is a top, front, right side perspective view of the SWING SEAT showing the new design; Figure 2 is a left side view thereof; Figure 3 is a right side view thereof; Figure 4 is a front view thereof; Figure 5 is a rear view thereof; Figure 6 is a top view thereof; Figure 7 is a bottom view thereof; Figure 8 is an environmental view thereof; Figure 9 is a first variant of the SWING SEAT showing a top, front, right side perspective view thereof; Figure 10 is a left side view thereof; Figure 11 is a right side view thereof; Figure 12 is a front view thereof; Figure 13 is a rear view thereof; Figure 14 is a top view thereof; Figure 15 is a bottom view thereof; Figure 16 is a second variant of the SWING SEAT showing a top, front, right side perspective view thereof; Figure 17 is a left side view thereof; Figure 18 is a right side view thereof; Figure 19 is a front view thereof; Figure 20 is a rear view thereof; Figure 21 is a top view thereof; and Figure 22 is a bottom view thereof. Drawings of the design are included.