Update openai requirement in /samples/durable-functions/python (#372)

Updates the requirements on [openai](https://github.com/openai/openai-python) to permit the latest version.
- [Release notes](https://github.com/openai/openai-python/releases)
- [Changelog](https://github.com/openai/openai-python/blob/main/CHANGELOG.md)
- [Commits](openai/openai-python@v2.44.0...v3.6.0)

---
updated-dependencies:
- dependency-name: openai
  dependency-version: 3.6.0
  dependency-type: direct:production
...

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Author: dependabot[bot]

samples/durable-functions/python/agent-directed-workflows/requirements.txt

@@ -1,5 +1,5 @@
 azure-functions
 azure-functions-durable
 redis
-openai>=2.44.0
+openai>=3.6.0
 azure-identity>=1.25.3