The ‘action’ method was deprecated in Shepherd 0.10.0.
* gnu/services/base.scm (shepherd-set-http-proxy-action)
(shepherd-discover-action): Use ‘perform-service-action’ instead of the
now-deprecated ‘action’ method.
Change-Id: Ibe1c79a44148596292c2c8907011ec787f8a9ddd