Update rock

[alithethird]

Updated the indico-nginx-rock base, updated the nginx-prometheus-exporter from a snap to source. Pinned the websockets version.

Overview

Rationale

indico-nginx-rock base should have been updated when indico-rock base was updated so fixing that now.
nginx-prometheus-exporter snap was using old golang and had some security issues.
websockets needs to be pinned.

Juju Events Changes

Module Changes

Library Changes

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated
• The PR is tagged with appropriate label (urgent, trivial, complex)