The ornamental design for a beveragecontainer, as shown and described.
FIG. 1 is a rear top isometric view of a first embodiment of a beverage container showing my new design;
FIG. 2 is a first side view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a second side view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a rear top isometric view of a second embodiment of a beverage container, all sides being the same as FIGS. 1-7 save for the unclaimed tethered lid.