Bump transformers from 4.38.0 to 4.48.0 in /examples/research_projects/pplm (#36540)

Bump transformers in /examples/research_projects/pplm

Bumps [transformers](https://github.com/huggingface/transformers) from 4.38.0 to 4.48.0.
- [Release notes](https://github.com/huggingface/transformers/releases)
- [Commits](v4.38.0...v4.48.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

examples/research_projects/pplm/requirements.txt

@@ -19,4 +19,4 @@ pytest
 conllu
 sentencepiece != 0.1.92
 protobuf
-transformers==4.38.0
+transformers==4.48.0