chore(deps): bump the python group in /backend with 2 updates

Bumps the python group in /backend with 2 updates: [django](https://github.com/django/django) and [django-model-utils](https://github.com/jazzband/django-model-utils).


Updates `django` from 5.1 to 5.1.1
- [Commits](django/django@5.1...5.1.1)

Updates `django-model-utils` from 4.5.1 to 5.0.0
- [Release notes](https://github.com/jazzband/django-model-utils/releases)
- [Changelog](https://github.com/jazzband/django-model-utils/blob/master/CHANGES.rst)
- [Commits](jazzband/django-model-utils@4.5.1...5.0.0)

---
updated-dependencies:
- dependency-name: django
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: python
- dependency-name: django-model-utils
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: python
...

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

backend/requirements.txt

@@ -12,7 +12,7 @@ beautifulsoup4==4.12.3
     # via -r requirements.in
 dj-database-url==2.2.0
     # via -r requirements.in
-django==5.1
+django==5.1.1
     # via
     #   -r requirements.in
     #   dj-database-url
@@ -25,7 +25,7 @@ django-apscheduler==0.6.2
     # via -r requirements.in
 django-filter==24.3
     # via -r requirements.in
-django-model-utils==4.5.1
+django-model-utils==5.0.0
     # via -r requirements.in
 djangorestframework==3.15.2
     # via