That does not contain the snapshot version of the module. You can compile it from here: https://github.com/openmrs/openmrs-module-webservices.rest
Or download it from here and rename the file from .jar
to .omod
https://openmrs.jfrog.io/ui/repos/tree/General/snapshots%2Forg%2Fopenmrs%2Fmodule%2Fwebservices.rest-omod%2F2.28.0-SNAPSHOT%2Fwebservices.rest-omod-2.28.0-20200218.225609-1.jar