Bump fastapi-slim from 0.115.5 to 0.115.6

Bumps [fastapi-slim](https://github.com/fastapi/fastapi) from 0.115.5 to 0.115.6.
- [Release notes](https://github.com/fastapi/fastapi/releases)
- [Commits](fastapi/fastapi@0.115.5...0.115.6)

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

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