fix: Fix from_dict of DocumentPreprocessor super component

[sjrl]

Related Issues

• fixes #issue-number

Proposed Changes:

Updates from_dict to handle splitting_function: None

How did you test it?

Updated from_dict test for this behavior

Notes for the reviewer

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[julian-risch]

LGTM! 👍

[coveralls]

Pull Request Test Coverage Report for Build 14588482131

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.02%) to 90.479%

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Files with Coverage Reduction	New Missed Lines	%
components/preprocessors/document_preprocessor.py	1	95.56%
core/pipeline/async_pipeline.py	3	67.32%

Totals
Change from base Build 14532049680:	-0.02%
Covered Lines:	10814
Relevant Lines:	11952

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💛 - Coveralls