Bump transformers in /examples/ray/batch-split-proxy/training

Bumps [transformers](https://github.com/huggingface/transformers) from 3.2.0 to 4.38.0.
- [Release notes](https://github.com/huggingface/transformers/releases)
- [Commits](huggingface/transformers@v3.2.0...v4.38.0)

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

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

examples/ray/batch-split-proxy/training/requirements.txt

@@ -4,4 +4,4 @@ scikit-learn==0.23.2
 simpletransformers==0.48.5
 # tensorboardX==1.9
 torch==1.6.0
-transformers==3.2.0
+transformers==4.38.0