build(deps): update boto3 requirement in /lambdas/pdf-extract

Updates the requirements on [boto3](https://github.com/boto/boto3) to permit the latest version.
- [Release notes](https://github.com/boto/boto3/releases)
- [Commits](https://github.com/boto/boto3/compare/1.43.46...1.43.51)

---
updated-dependencies:
- dependency-name: boto3
  dependency-version: 1.43.51
  dependency-type: direct:production
...

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

lambdas/pdf-extract/requirements.txt

@@ -1,3 +1,3 @@
 pdfplumber>=0.11.10,<1.0
-boto3>=1.43.46,<2.0
+boto3>=1.43.51,<2.0
 httpx>=0.28.1,<1.0