Try to add celery in CI

.github/workflows/django.yml

@@ -26,6 +26,8 @@ jobs:
           - 5432:5432
         # needed because the postgres container does not provide a healthcheck
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
+      redis:
+        image: redis
 
     env:
       DATABASE_URL: "postgres://${{ vars.DATABASE_USER }}:${{ vars.DATABASE_PASSWORD }}@${{ vars.DATABASE_HOST }}:${{ vars.DATABASE_PORT }}/${{ vars.DATABASE_NAME }}"

conftest.py

@@ -0,0 +1,8 @@
+import pytest
+
+pytest_plugins = ("celery.contrib.pytest",)
+
+
+@pytest.fixture(scope="session")
+def celery_config():
+    return {"broker_url": "redis://", "result_backend": "redis://"}

gsl_demarches_simplifiees/tests/test_dossier_converter.py

@@ -11,7 +11,11 @@
     Dossier,
 )
 
-pytestmark = pytest.mark.django_db
+pytestmark = [
+    pytest.mark.django_db,
+    pytest.mark.usefixtures("celery_session_app"),
+    pytest.mark.usefixtures("celery_session_worker"),
+]
 
 
 @pytest.fixture