build(deps): bump djangorestframework-simplejwt in /backend/requirements

Bumps [djangorestframework-simplejwt](https://github.com/jazzband/djangorestframework-simplejwt) from 5.3.0 to 5.3.1.
- [Release notes](https://github.com/jazzband/djangorestframework-simplejwt/releases)
- [Changelog](https://github.com/jazzband/djangorestframework-simplejwt/blob/master/CHANGELOG.md)
- [Commits](jazzband/djangorestframework-simplejwt@v5.3.0...v5.3.1)

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

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

backend/requirements/base.txt

@@ -12,7 +12,7 @@ flower==2.0.1  # https://github.com/mher/flower
 # Django
 # ------------------------------------------------------------------------------
 django==4.2.7 # https://www.djangoproject.com/
-djangorestframework-simplejwt==5.3.0 # https://github.com/jazzband/djangorestframework-simplejwt
+djangorestframework-simplejwt==5.3.1 # https://github.com/jazzband/djangorestframework-simplejwt
 django-health-check==3.17.0 # https://github.com/revsys/django-health-check
 django-environ==0.11.2 # https://github.com/joke2k/django-environ
 django-celery-beat==2.5.0  # https://github.com/celery/django-celery-beat