stack/monitor: Remove unused gzip dependency

stack/monitor/buildout.cfg

@@ -93,7 +93,6 @@ template = ${:_profile_base_location_}/instance-monitor.cfg.jinja2.in
 rendered = ${buildout:directory}/template-monitor.cfg
 context =
     key apache_location apache:location
-    key gzip_location gzip:location
     key template_logrotate_base template-logrotate-base:rendered
     raw monitor_bin ${buildout:directory}/bin/monitor.bootstrap
     raw monitor_collect ${buildout:directory}/bin/monitor.collect