chore(deps): bump pypdf in the pip group across 1 directory

Bumps the pip group with 1 update in the / directory: [pypdf](https://github.com/py-pdf/pypdf).


Updates `pypdf` from 6.1.3 to 6.4.0
- [Release notes](https://github.com/py-pdf/pypdf/releases)
- [Changelog](https://github.com/py-pdf/pypdf/blob/main/CHANGELOG.md)
- [Commits](py-pdf/pypdf@6.1.3...6.4.0)

---
updated-dependencies:
- dependency-name: pypdf
  dependency-version: 6.4.0
  dependency-type: direct:production
  dependency-group: pip
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

pyproject.toml

@@ -50,7 +50,7 @@ dependencies = [
     "xlrd==2.0.2",
     "xlwt==1.3.0",
     "pymupdf==1.26.3",
-    "pypdf==6.1.3",
+    "pypdf==6.4.0",
     "pydub==0.25.1",
     "pysilk==0.0.1",
     "gunicorn==23.0.0",