I claim the ornamental design for a gas flow regulator, as shown and described.
FIG. 1 is a perspective view of the gas flow regulator showing my new design.
FIG. 2 is a first side view of the gas flow regulator.
FIG. 3 is a second side view of the gas flow regulator.
FIG. 4 is a front view of the gas flow regulator.
FIG. 5 is a rear view of the gas flow regulator.
FIG. 6 is a top plan view of the gas flow regulator; and,
FIG. 7 is a bottom plan view of the gas flow regulator.
The broken lines shown in the figures are included for the purpose of illustrating portions of the gas flow regulator and form no part of the claimed design.