Replace django-background-tasks with huey (#657)

* Replace django-background-tasks with huey

* Add command for migrating tasks

* Add custom admin view

* fix dockerfile

* fix tests

* fix tests in CI

* fix task tests

* implement retries

* improve config

* workaround to avoid running singlefile tasks in parallel

* properly kill single-file sub-processes

* use period task for HTML snapshots

* clear task lock when starting task consumer

* remove obsolete cleanup task command

.github/workflows/main.yaml

@@ -24,7 +24,9 @@ jobs:
       - name: Install Node dependencies
         run: npm ci
       - name: Setup Python environment
-        run: pip install -r requirements.txt -r requirements.dev.txt
+        run: |
+          pip install -r requirements.txt -r requirements.dev.txt
+          mkdir data
       - name: Run tests
         run: python manage.py test bookmarks.tests
   e2e_tests:
@@ -47,6 +49,7 @@ jobs:
         run: |
           pip install -r requirements.txt -r requirements.dev.txt
           playwright install chromium
+          mkdir data
       - name: Run build
         run: |
           npm run build