Bump pymupdf from 1.23.20 to 1.23.21

Bumps [pymupdf](https://github.com/pymupdf/pymupdf) from 1.23.20 to 1.23.21.
- [Release notes](https://github.com/pymupdf/pymupdf/releases)
- [Changelog](https://github.com/pymupdf/PyMuPDF/blob/main/changes.txt)
- [Commits](pymupdf/PyMuPDF@1.23.20...1.23.21)

---
updated-dependencies:
- dependency-name: pymupdf
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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