feature/skip None values when merging

[cutoffthetop]

PR Context

• this broke the merging of optional fields, e.g. on ExtractedResources

Fixed

• skip None values when merging extracted and rule items

[esinsj]

I have a few questions to be able to review this PR:

1. the Changelog says "skip None-values" but e.g. extending adds None-values and pruning removes them if they are given as a list (i.e. [None]). Is that relevant?
2. For the pruning, a searched fieldname which should have a value removed, but which is non-existent in the dict, is not ignored but instead added to the dict as a new key. Is this the desired behavior? (e.g. see test_utils line 59ff)

[cutoffthetop]

1. the Changelog says "skip None-values" but e.g. extending adds None-values and pruning removes them if they are given as a list (i.e. [None]). Is that relevant?

[None] is not (yet) relevant, because the input to the merging would be Extracted- and Rule-items - neither have fields that allow a None inside a list.

2. For the pruning, a searched fieldname which should have a value removed, but which is non-existent in the dict, is not ignored but instead added to the dict as a new key. Is this the desired behavior? (e.g. see test_utils line 59ff)

good observation, but this is also valid behavior for the merging use-case. because the resulting dict will be parsed into a AnyMergedItem (model_validate). and a key-value pair with an empty list as a value, is basically the same as not having the key.