chore(deps): Bump openai from 1.37.0 to 1.39.0 in /examples/functions

Bumps [openai](https://github.com/openai/openai-python) from 1.37.0 to 1.39.0.
- [Release notes](https://github.com/openai/openai-python/releases)
- [Changelog](https://github.com/openai/openai-python/blob/main/CHANGELOG.md)
- [Commits](openai/openai-python@v1.37.0...v1.39.0)

---
updated-dependencies:
- dependency-name: openai
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

examples/functions/requirements.txt

@@ -1,2 +1,2 @@
 langchain==0.2.12
-openai==1.37.0
+openai==1.39.0