Bump pypdf from 4.1.0 to 4.3.1

Bumps [pypdf](https://github.com/py-pdf/pypdf) from 4.1.0 to 4.3.1.
- [Release notes](https://github.com/py-pdf/pypdf/releases)
- [Changelog](https://github.com/py-pdf/pypdf/blob/main/CHANGELOG.md)
- [Commits](https://github.com/py-pdf/pypdf/compare/4.1.0...4.3.1)

---
updated-dependencies:
- dependency-name: pypdf
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -6,7 +6,7 @@ langchain-community==0.0.29
 langchain-experimental==0.0.55
 backoff==2.2.1
 toml
-pypdf==4.1.0
+pypdf==4.3.1
 ratelimit==2.2.1
 loguru==0.7.2
 pydantic==2.8.2