I claim the ornamental design for a digital lock, as shown and described.
FIG. 1 is a front side, bottom perspective view of the digital lock showing my design;
FIG. 2 is a front elevation view of the digital lock;
FIG. 3 is a rear elevation view of the digital lock;
FIG. 4 is a top elevation view of the digital lock;
FIG. 5 is a bottom elevation view of the digital lock;
FIG. 6 is a left elevation view of the digital lock; and,
FIG. 7 is a right elevation view of the digital lock.
The broken line showing of digital lock is included for the purpose of illustrating portions of the digital lock that form no part of the claimed design.