Add ModelList to ModelContainer parents

[tapastro]

This PR adds a parent ABC to ModelContainer, so that behavior in stpipe can be altered if step/pipeline input is a ModelContainer rather than a JwstDataModel.

Need to wait for stdatamodels release containing ModelList addition (currently expected to be 0.4.4.)

Checklist

• [x] added entry in CHANGES.rst within the relevant release section
• [ ] updated or added relevant tests
• [ ] updated relevant documentation
• [x] added relevant milestone
• [x] added relevant label(s)

[tapastro]

I wrote this thinking Sequence existed only as a 'marker' parent class, i.e. we weren't using any of its functionality in ModelContainer. Do you know if this is true or not?

I tried to verify by putting all of my PRs on this project from stpipe/stdatmodels/jwst in one environment, and while I don't see any errors, there could be an error in how I put all of the new code in the conda environment... 🤷

[stscieisenhamer]

Ah, if Sequence is only a marker also, then should it be removed completely, since that is what ModelList is supposed to do?

[tapastro]

Ah, if Sequence is only a marker also, then should it be removed completely, since that is what ModelList is supposed to do?

I just wrote out a message saying that's what my PRs intended to do, then checked to see I left Sequence in the list of parent classes... I'll have to run the local tests again to see if Sequence is necessary.

[stscieisenhamer]

This PR is still marked as draft. When ready, please rebase and un-draft.

[tapastro]

This is no longer marked as draft, but it does rely on a new stdatamodels build before merging can be performed.

[stscieisenhamer]

is this still relevant?