build(deps): bump locust from 2.32.8 to 2.32.9 in /backend

Bumps [locust](https://github.com/locustio/locust) from 2.32.8 to 2.32.9.
- [Release notes](https://github.com/locustio/locust/releases)
- [Changelog](https://github.com/locustio/locust/blob/master/docs/changelog.rst)
- [Commits](locustio/locust@2.32.8...2.32.9)

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

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

backend/requirements.txt

@@ -19,4 +19,4 @@ numpy<3.0.0
 pytest==8.3.4
 coverage==7.6.12
 Faker==35.2.0
-locust==2.32.8
+locust==2.32.9