Bump pypdf from 4.2.0 to 6.6.0

Bumps [pypdf](https://github.com/py-pdf/pypdf) from 4.2.0 to 6.6.0.
- [Release notes](https://github.com/py-pdf/pypdf/releases)
- [Changelog](https://github.com/py-pdf/pypdf/blob/main/CHANGELOG.md)
- [Commits](py-pdf/pypdf@4.2.0...6.6.0)

---
updated-dependencies:
- dependency-name: pypdf
  dependency-version: 6.6.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

setup.py

@@ -109,7 +109,7 @@ def _write_version_file():
         "pylint==3.3.4",
         "pyproj==3.7.1",
         "python==3.13",
-        "pypdf==6.4.0",
+        "pypdf==6.6.0",
         "requests==2.32.4",
         "scipy==1.15.2",
         "sparselt==0.1.3",