Bump openai from 1.12.0 to 1.48.0

Bumps [openai](https://github.com/openai/openai-python) from 1.12.0 to 1.48.0.
- [Release notes](https://github.com/openai/openai-python/releases)
- [Changelog](https://github.com/openai/openai-python/blob/main/CHANGELOG.md)
- [Commits](https://github.com/openai/openai-python/compare/v1.12.0...v1.48.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements.txt

@@ -13,7 +13,7 @@ h11==0.14.0
 httpcore==1.0.5
 httpx==0.27.2
 idna==3.10
-openai==1.12.0
+openai==1.48.0
 packaging==24.0
 pydantic==2.9.2
 pydantic_core==2.16.2