[deps] Update pytest-django requirement from ~=4.8.0 to ~=4.9.0

Updates the requirements on [pytest-django](https://github.com/pytest-dev/pytest-django) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest-django/releases)
- [Changelog](https://github.com/pytest-dev/pytest-django/blob/main/docs/changelog.rst)
- [Commits](pytest-dev/pytest-django@v4.8.0...v4.9.0)

---
updated-dependencies:
- dependency-name: pytest-django
  dependency-type: direct:production
...

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

requirements-test.txt

@@ -1,6 +1,6 @@
 responses~=0.25.3
 pytest-asyncio~=0.24.0
-pytest-django~=4.8.0
+pytest-django~=4.9.0
 freezegun~=1.5.1
 # Needed to test integrations
 openwisp-monitoring @ https://github.com/openwisp/openwisp-monitoring/tarball/master