Preserve newlines in Table and TableChunk elements during PDF partitioning

[eureka928]

Closes #3983

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Summary

This PR fixes an issue where newline characters were being incorrectly stripped from Table and TableChunk elements during PDF partitioning. The RE_MULTISPACE_INCLUDING_NEWLINES regex was being applied indiscriminately to all Text elements, including tables, which removed newlines that carry structural meaning (such as row separation).

Changes

• unstructured/partition/pdf.py: Added conditional logic to skip whitespace normalization for Table and TableChunk elements, preserving newlines that convey tabular structure
• CHANGELOG.md: Added entry documenting the fix
• unstructured/__version__.py: Version bump to 0.18.33

Problem

When processing PDFs (especially image-based PDFs with tables), the code applied this regex substitution to all Text elements:

el.text = re.sub(RE_MULTISPACE_INCLUDING_NEWLINES, " ", el.text or "").strip()

This stripped meaningful line breaks from table content, degrading the structural representation of tabular data.

Solution

Added a check to exclude Table and TableChunk elements from the whitespace normalization:

# Skip newline normalization for Table/TableChunk - newlines carry structural meaning
if not isinstance(el, (Table, TableChunk)):
    el.text = re.sub(
        RE_MULTISPACE_INCLUDING_NEWLINES,
        " ",
        el.text or "",
    ).strip()

[badGarnet]

the ingest test is failing because multiple white space used to be replaced with just one but now they remain multiple ones -> results in text changed

• the ticket only asked for new lines to be preserved and that seem reasonable for tables
• but multiple white space (excluding new lines, so like two space together ) should still be replaced with just one to improve readability of the extracted content