Bump pypdf from 6.1.3 to 6.4.0 in /app/functions/figure_processor

Bumps [pypdf](https://github.com/py-pdf/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
...

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

Author: dependabot[bot]

app/functions/figure_processor/requirements.txt

@@ -349,7 +349,7 @@ pyjwt==2.10.1
     #   msal
 pymupdf==1.26.0
     # via -r requirements.in
-pypdf==6.1.3
+pypdf==6.4.0
     # via -r requirements.in
 python-dotenv==1.1.1
     # via