FIG. 1 is a front perspective view of a shower control showing our design; FIG. 2 is a front elevational view thereof; FIG. 3 is a left side elevational view thereof; FIG. 4 is a right side elevational view thereof; FIG. 5 is a top plan view thereof; and, FIG. 6 is a bottom plan view thereof. The broken lines in the Figures are for illustrative purposes only and form no part of the claimed design.