The ornamental design for a holsterconnection, as shown and described.
FIG. 1 is a front perspective view of a holster connection showing the new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a top plan view thereof; and,
FIG. 5 is a bottom plan view thereof.
The broken line showing of portions of the holster connection is included for illustrating environmental structure and forms no part of the claimed design.