Bump uvicorn from 0.49.0 to 0.50.0 in /backend

Bumps [uvicorn](https://github.com/Kludex/uvicorn) from 0.49.0 to 0.50.0.
- [Release notes](https://github.com/Kludex/uvicorn/releases)
- [Changelog](https://github.com/Kludex/uvicorn/blob/main/docs/release-notes.md)
- [Commits](Kludex/uvicorn@0.49.0...0.50.0)

---
updated-dependencies:
- dependency-name: uvicorn
  dependency-version: 0.50.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/pyproject.toml

@@ -29,7 +29,7 @@ dependencies = [
     "types-aiofiles==25.1.0.20251011",
     "types-passlib==1.7.7.20241221",
     "types-simplejson==3.20.0.20250218",
-    "uvicorn==0.49.0",
+    "uvicorn==0.50.0",
 ]
 
 [tool.pytest.ini_options]