perf: upgrade pdfminer-six to 20260107 (#4168)
Fixes ~15-18% performance regression introduced in 20251230 where
f-strings were evaluated eagerly even when logging was disabled.
See: https://github.com/pdfminer/pdfminer.six/issues/1233
Fix: https://github.com/pdfminer/pdfminer.six/pull/1234
<!-- CURSOR_SUMMARY -->
---
> [!NOTE]
> Restores PDF parsing performance by updating dependency and releasing
a new dev version.
>
> - **Deps:** Upgrade `pdfminer-six` from `20251230` to `20260107` in
`requirements/extra-pdf-image.txt` to fix ~15–18% slowdown from eager
f-string evaluation in logging
> - **Release:** Bump `__version__` to `0.18.27-dev5` and add CHANGELOG
entry under *Enhancement*
>
> <sup>Written by [Cursor
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<!-- /CURSOR_SUMMARY -->
