Container holder

1. 1The ornamental design for a container holder as shown and described.

FIG. 1 is a top, front perspective view of a container holder showing my new design;
FIG. 2 is a bottom, rear perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a side view thereof;
FIG. 6 is an opposite side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines immediately adjacent to the shaded area define the bounds of the claimed design and form no part thereof. The broken lines depicting the remainder of the container holder form no part of the claimed design.