Bump openai from 1.47.0 to 1.50.2 in /backend (OWASP#18)

Bumps [openai](https://github.com/openai/openai-python) from 1.47.0 to 1.50.2.
- [Release notes](https://github.com/openai/openai-python/releases)
- [Changelog](https://github.com/openai/openai-python/blob/main/CHANGELOG.md)
- [Commits](openai/openai-python@v1.47.0...v1.50.2)

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

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

Author: dependabot[bot]

backend/poetry.lock

@@ -31,7 +31,7 @@ gunicorn = "^23.0.0"
 humanize = "^4.10.0"
 lxml = "^5.3.0"
 markdown = "^3.7"
-openai = "^1.45.0"
+openai = "^1.50.2"
 psycopg2 = "^2.9.9"
 pygithub = "^2.3.0"
 python = "^3.12"