chore(deps): bump django-celery-beat from 2.8.1 to 2.9.0 in /backend (baserow#5296)

Bumps [django-celery-beat](https://github.com/celery/django-celery-beat) from 2.8.1 to 2.9.0.
- [Release notes](https://github.com/celery/django-celery-beat/releases)
- [Changelog](https://github.com/celery/django-celery-beat/blob/main/Changelog)
- [Commits](celery/django-celery-beat@v2.8.1...v2.9.0)

---
updated-dependencies:
- dependency-name: django-celery-beat
  dependency-version: 2.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

backend/pyproject.toml

@@ -37,7 +37,7 @@ dependencies = [
     "django-celery-email-reboot==4.2.0",
     "zipp==3.23.0",
     "unicodecsv==0.14.1",
-    "django-celery-beat==2.8.1",
+    "django-celery-beat==2.9.0",
     "celery-redbeat==2.3.3",
     "flower==2.0.1",
     "service-identity==24.2.0",