The ornamental design for a container, as shown and described.
FIG. 1 is a top perspective view of a container, showing my new design.
FIG. 2 is a side elevational view thereof.
FIG. 3 is a front and rear elevational view thereof.
FIG. 4 is a top plan view thereof; and,
FIG. 5 is a bottom plan view thereof.
The broken lines showing scored lines on the container are for the purpose of illustrating environmental structure and unclaimed subject matter and form no part of the claimed design.