The ornamental design for a gasregulator, as shown and described.
FIG. 1 is a front perspective view of a gas regulator showing our new design;
FIG. 2 is a rear perspective thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a front view thereof; and,
FIG. 6 is a top view thereof.
The broken lines shown in the figures are included for the purpose of illustrating portions of the gas regulator and form no part of the claimed design.