Bump keras from 2.8.0 to 2.13.1 in /examples/research_projects/decision_transformer (#32393)

Bump keras in /examples/research_projects/decision_transformer

Bumps [keras](https://github.com/keras-team/keras) from 2.8.0 to 2.13.1.
- [Release notes](https://github.com/keras-team/keras/releases)
- [Commits](https://github.com/keras-team/keras/compare/v2.8.0...v2.13.1

)

---
updated-dependencies:
- dependency-name: keras
  dependency-type: direct:production
...
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

examples/research_projects/decision_transformer/requirements.txt

@@ -97,7 +97,7 @@ jinja2-time==0.2.0
 jmespath==0.10.0
 joblib==1.2.0
 jsonschema==4.4.0
-keras==2.8.0
+keras==2.13.1
 Keras-Preprocessing==1.1.2
 kiwisolver==1.4.0
 kubernetes==12.0.1