Make bypass setup and run update invalid in static models

[dalonsoa]

Description

This PR removes the possibility of skipping running the _setup method but still running _update once, which is an invalid configuration for static models.

As an extra, a bug is fixed by which the _update method was run in static models if no variables were present and None were required. If None are required, then the updated method should not run. Granted that is unlikely to happen in a real scenario, yet it should not happen ever.

Fixes #687

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist

• Make sure you've run the pre-commit checks: $ pre-commit run -a
• All tests pass: $ poetry run pytest

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works
• Relevant documentation reviewed and updated

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.75%. Comparing base (8aa5af7) to head (d589958).
Report is 805 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #693      +/-   ##
===========================================
+ Coverage    94.74%   94.75%   +0.01%     
===========================================
  Files           73       73              
  Lines         4984     4995      +11     
===========================================
+ Hits          4722     4733      +11     
  Misses         262      262              

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[sallymatson]

Great - I'll add this specification in the docs as well.

[vgro]

Looks fine to me

[davidorme]

The logic looks solid but a couple of things I'm not so clear on.

[dalonsoa]

@davidorme , I think I implemented all the changes requested here. Shall we merge, so it does not become stalled?

[davidorme]

LGTM