Bump importlib-metadata from 8.7.1 to 9.0.0 in /back-end

Bumps [importlib-metadata](https://github.com/python/importlib_metadata) from 8.7.1 to 9.0.0.
- [Release notes](https://github.com/python/importlib_metadata/releases)
- [Changelog](https://github.com/python/importlib_metadata/blob/main/NEWS.rst)
- [Commits](python/importlib_metadata@v8.7.1...v9.0.0)

---
updated-dependencies:
- dependency-name: importlib-metadata
  dependency-version: 9.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

back-end/requirements.txt

@@ -7,7 +7,7 @@ fastapi==0.133.0
 h11==0.16.0
 idna==3.11
 immutables==0.21
-importlib-metadata==8.7.1
+importlib-metadata==9.0.0
 pydantic==2.12.5
 python-multipart==0.0.22
 six==1.17.0