✨(backend) update Docker Hub workflow and fix migration conflict

- Added 'feature/doc-dnd' branch to the Docker Hub workflow to support
new feature development.
- Created a new migration to add the 'has_deleted_children' field to the
document model, enhancing the management of document states.

.github/workflows/docker-hub.yml

@@ -6,6 +6,7 @@ on:
   push:
     branches:
       - 'main'
+      - 'feature/doc-dnd'
     tags:
       - 'v*'
   pull_request:

src/backend/core/migrations/0022_remove_document_is_public_and_more.py

@@ -5,7 +5,7 @@ from django.db import migrations, models
 
 class Migration(migrations.Migration):
     dependencies = [
-        ("core", "0020_remove_is_public_add_field_attachments_and_duplicated_from"),
+        ("core", "0021_activate_unaccent_extension"),
     ]
 
     operations = [