fix: Update photo deletion test to assert deleted_count instead of deleted

The test for photo deletion now checks for "deleted_count" in the response data, ensuring that the count of deleted photos is non-negative. This change aligns the test with the actual API response structure.

tests/test_api_photos.py

@@ -395,7 +395,8 @@ class TestPhotoDeletion:
         
         assert response.status_code == 200
         data = response.json()
-        assert "deleted" in data
+        assert "deleted_count" in data
+        assert data["deleted_count"] >= 0
 
     def test_bulk_delete_photos_non_admin(
         self,