🎨 Bring Python code into compliance with Black and Flake8 (#121)

* Ignore Flake8 unused import error F401

https://flake8.readthedocs.io/en/latest/user/error-codes.html

The apparently unused imports may be needed for SQLAlchemy.

As the code comment says:

make sure all SQL Alchemy models are imported before initializing DB
otherwise, SQL Alchemy might fail to initialize properly relationships

See GitHub 28 and 29

* Ignore Flake8 unused variable error F841

https://flake8.readthedocs.io/en/latest/user/error-codes.html

The apparently unused variables may be needed for tests.

* Bring line length into compliance with Black

Should be 88 characters.

* Format alembic code with Black

{{cookiecutter.project_slug}}/backend/app/app/schemas/item.py

@@ -1,6 +1,7 @@
 from pydantic import BaseModel
 
-from .user import User
+from .user import User  # noqa: F401
+
 
 # Shared properties
 class ItemBase(BaseModel):