bump nixpkgs version

See merge request !327

Bump megacli version to fix exception handling

See merge request !321

Configure production grid monitoring to also use new 2nd level domain

See merge request !324

refs privatestorageops#416, PrivateStorageio#115

Automatically create production update MRs

See merge request !318

bump nixpkgs version

See merge request !320

Re-add stages

See merge request !317

So expand it ourselves

GitLab docs explicitly say `needs` does not require stages but GitLab actual behavior is:

```
Found errors in your .gitlab-ci.yml:

    update-staging job needs system-tests job, but system-tests is not in any previous stage
    update-staging job needs morph-build-staging job, but morph-build-staging is not in any previous stage

```

Automate updating nixpkgs pin in develop branch once a week

See merge request !305

The default is `when: "on_success"` which is equivalent to "always" since we
have no stages.

Some terminal code stripping logic added though