chore(deps): bump django in /appengine/flexible/django_cloudsql (#13630)

Bumps [django](https://github.com/django/django) from 5.2.5 to 5.2.8.
- [Commits](django/django@5.2.5...5.2.8)

---
updated-dependencies:
- dependency-name: django
  dependency-version: 5.2.8
  dependency-type: direct:production
...

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

Author: dependabot[bot]

appengine/flexible/django_cloudsql/requirements.txt

@@ -1,4 +1,4 @@
-Django==5.2.5
+Django==5.2.8
 gunicorn==23.0.0
 psycopg2-binary==2.9.10
 django-environ==0.12.0