Update transformers requirement

Updates the requirements on [transformers](https://github.com/huggingface/transformers) to permit the latest version.
- [Release notes](https://github.com/huggingface/transformers/releases)
- [Commits](https://github.com/huggingface/transformers/compare/v4.39.0...v4.56.1)

---
updated-dependencies:
- dependency-name: transformers
  dependency-version: 4.56.1
  dependency-type: direct:production
...

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

requirements.txt

@@ -1,5 +1,5 @@
 torch>=2.1.1,<3.0
-transformers>=4.39.0,<4.51.0
+transformers>=4.39.0,<4.57.0
 asyncio>=3.4.3,<5.0
 toml
 pypdf==5.1.0