Require Socket
Require Socket

6bbbc22de454d94192ed7393d7b767071f3d73fa introduced a default scheme by
using `Socket.gethostname` to use the system's hostname.  However,
Socket was not required here, resulting in errors.

sensu-plugins/sensu-plugins-process-checks,sensu-plugins/sensu-plugins-process-checks,sensu-plugins/sensu-plugins-process-checks,tomduckering/sensu-plugins-process-checks,tomduckering/sensu-plugins-process-checks,tomduckering/sensu-plugins-process-checks