♻️ Refactor backend, settings, DB sessions, types, configs, plugins (#158)

* ♻️ Refactor backend, update DB session handling

* ✨ Add mypy config and plugins

* ➕ Use Python-jose instead of PyJWT

as it has some extra functionalities and features

* ✨ Add/update scripts for test, lint, format

* 🔧 Update lint and format configs

* 🎨 Update import format, comments, and types

* 🎨 Add types to config

* ✨ Add types for all the code, and small fixes

* 🎨 Use global imports to simplify exploring with Jupyter

* ♻️ Import schemas and models, instead of each class

* 🚚 Rename db_session to db for simplicity

* 📌 Update dependencies installation for testing

{{cookiecutter.project_slug}}/backend/app/app/worker.py

@@ -1,11 +1,11 @@
 from raven import Client
 
-from app.core.config import settings
 from app.core.celery_app import celery_app
+from app.core.config import settings
 
 client_sentry = Client(settings.SENTRY_DSN)
 
 
 @celery_app.task(acks_late=True)
-def test_celery(word: str):
+def test_celery(word: str) -> str:
     return f"test task return {word}"