build(deps): bump transformers in /backend/requirements

Bumps [transformers](https://github.com/huggingface/transformers) from 4.49.0 to 4.53.0.
- [Release notes](https://github.com/huggingface/transformers/releases)
- [Commits](huggingface/transformers@v4.49.0...v4.53.0)

---
updated-dependencies:
- dependency-name: transformers
  dependency-version: 4.53.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

backend/requirements/default.txt

@@ -83,7 +83,7 @@ supervisor==4.2.5
 RapidFuzz==3.13.0
 tiktoken==0.7.0
 timeago==1.0.16
-transformers==4.49.0
+transformers==4.53.0
 unstructured==0.15.1
 unstructured-client==0.25.4
 uvicorn==0.21.1

backend/requirements/model_server.txt

@@ -12,7 +12,7 @@ sentence-transformers==4.0.2
 sentencepiece==0.2.0
 setfit==1.1.1
 torch==2.6.0
-transformers==4.49.0
+transformers==4.53.0
 uvicorn==0.21.1
 voyageai==0.2.3
 litellm==1.72.2