chore(deps) bump prometheus plugin to 0.6 (#5076)
chore(deps) bump prometheus plugin to 0.6 (#5076)

Changelog:
https://github.com/Kong/kong-plugin-prometheus/blob/master/CHANGELOG.md#060---20190929

Summary:
Metrics are now be available on the Status API
Kong/kong,Kong/kong,Mashape/kong,Kong/kong