⬆️ bump openai from 0.27.6 to 0.27.8 in /layer (#15)

Bumps [openai](https://github.com/openai/openai-python) from 0.27.6 to 0.27.8.
- [Release notes](https://github.com/openai/openai-python/releases)
- [Commits](openai/openai-python@v0.27.6...v0.27.8)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Gabriel Koo <hi@gabrielkoo.com>

layer/requirements.txt

@@ -1,4 +1,4 @@
-openai==0.27.6
+openai==0.27.8
 pandas==2.0.3
 slack_bolt==1.18.0
 slack_sdk