• net-mgmt/prometheus: Update from 1.6.3 to 1.7.1

• Changelog: https://github.com/prometheus/prometheus/releases/tag/v1.7.0 https://github.com/prometheus/prometheus/releases/tag/v1.7.1

PR: 220056
Submitted by: jevonearth (ports at ecadlabs.com) (maintainer)
Approved by: miwi (mentor)
Differential Revision: https://reviews.freebsd.org/D11273