fix: Use deepcopy instead of model_dump to copy view

[pkerpedjiev]

Description

Calling the .domain() function on a view creates a copy of the view. The current copy method dumps the view model and creates a new one from the view. Because views expect PluginTrack types instead of specific subclasses, the dumped model does not contain the class vars of the subclasses (e.g. PileupTrack). Switching to deepcopy preserves the class vars of the subclasses.

Here's the error that occurs in the added test without this change:

                    return pydantic_extra[item]
                except KeyError as exc:
>                   raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}') from exc
E                   AttributeError: 'PluginTrack' object has no attribute 'plugin_url'

Fixes #___

Checklist

• Unit tests added or updated
• Documentation added or updated
• Updated CHANGELOG.md

[nvictus]

Not familiar enough to know the consequences of deepcopy on a pydantic model, but pydantic appears to have this API:

Suggested change

	copy = deepcopy(model)
	copy = model.copy(deep=True)

[pkerpedjiev]

So that works too. I don't know what the difference is either but I switched over to model.model_copy (deep=True) (model.copy is deprecated).

[manzt]

Looks good to me! I'm surprised by the hack I had there before (rather than using .copy(deep=True). This is certainly an improvement.

[manzt]

Thanks for adding a test!