Bump uvicorn from 0.34.0 to 0.34.2 in /backend

Bumps [uvicorn](https://github.com/encode/uvicorn) from 0.34.0 to 0.34.2.
- [Release notes](https://github.com/encode/uvicorn/releases)
- [Changelog](https://github.com/encode/uvicorn/blob/master/docs/release-notes.md)
- [Commits](Kludex/uvicorn@0.34.0...0.34.2)

---
updated-dependencies:
- dependency-name: uvicorn
  dependency-version: 0.34.2
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]