Move TODO regarding pickling to markdown

[lgeiger]

Change Summary

As far as I can tell pickling is supported by pydantic, so I think this TODO in the docs can be removed.

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @adriangb

[codspeed-hq]

CodSpeed Performance Report

Merging #9288 will not alter performance

_{Comparing lgeiger:pickling-docs (ffcaa5d) with main (82e4664)}

Summary

✅ 13 untouched benchmarks

[lgeiger]

please review

[adriangb]

We'll have to get the test working to verify that!

[lgeiger]

We'll have to get the test working to verify that!

Sorry about that, I re-enabled the test. At least locally it seems to work as expected. Let's see what CI thinks.

[sydney-runkle]

Great, thank you!

[sydney-runkle]

Oh hmm, looks like this is still failing tests:

data = pickle.dumps(m)
E   _pickle.PicklingError: Can't pickle <class '__main__.FooBarModel'>: attribute lookup FooBarModel on __main__ failed

[lgeiger]

Yeah, looks like the failure just happens in the doctests. I moved the comment to a markdown such that it doesn't show up in the public docs which might confuse some users

[sydney-runkle]

Ah nice. Looks good!