The ornamental design for a growlercover, as shown and described.
FIG. 1 is a top and front perspective view of a growler cover, shown in use;
FIG. 2 is a top and front perspective view thereof;
FIG. 3 is a right elevation view thereof;
FIG. 4 is a left elevation view thereof;
FIG. 5 is a front elevation view thereof, which the opposing rear elevation is a mirror image thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The evenly spaced broken lines showing a growler in FIG. 1 depicts environmental subject matter that forms no part of the claimed design, while the remaining evenly spaced broken lines shown in the drawings depict portions of the growler cover that form no part of the claimed design. The unevenly spaced dash-dot-dash broken lines represent the bounds of the claimed design.