The ornamental design for beard trimmer, as shown and described.
1. Beard trimmer
Fig. 1.1 is a perspective view showing the beard trimmer of my design;
Fig. 1.2 is a front elevational view thereof;
Fig. 1.3 is a rear elevational view thereof;
Fig. 1.4 is a left side elevational view thereof;
Fig. 1.5 is a right side elevational view thereof;
Fig. 1.6 is a top plan view thereof; and
Fig. 1.7 is a bottom view thereof.
The portions of the beard trimmer shown in broken lines are included for the purpose of illustrating unclaimed portions of the beard trimmer and form no part of the claimed design.