Replaced flake8 and isort with ruff #468

Job	Run time
Check for news fragments in 'changelog.d/'	9s
Lint (black)	25s
Test Python 3.8, Django 3.2, Redis.py latest	2m 23s
Lint (ruff)	26s
Test Python 3.8, Django 4.0, Redis.py latest	2m 22s
Lint (mypy)	51s
Test Python 3.8, Django 4.1, Redis.py latest	2m 11s
Test Python 3.8, Django 4.2, Redis.py latest	2m 13s
Test Python 3.9, Django 3.2, Redis.py latest	2m 15s
Test Python 3.9, Django 4.0, Redis.py latest	2m 12s
Test Python 3.9, Django 4.1, Redis.py latest	2m 13s
Test Python 3.9, Django 4.2, Redis.py latest	2m 6s
Test Python 3.10, Django 3.2, Redis.py latest	2m 29s
Test Python 3.10, Django 4.0, Redis.py latest	2m 15s
Test Python 3.10, Django 4.1, Redis.py latest	2m 17s
Test Python 3.10, Django 4.2, Redis.py latest	2m 19s
Test Python 3.6, Django 3.2, Redis.py latest	2m 32s
Test Python 3.7, Django 3.2, Redis.py latest	2m 30s
Test Python 3.11, Django 4.1, Redis.py latest	2m 13s
Test Python 3.11, Django 4.2, Redis.py latest	2m 8s
Test Python 3.11, Django 4.2, Redis.py master	2m 25s
Test Python 3.11, Django main, Redis.py latest	2m 26s
Test Python 3.11, Django main, Redis.py master	2m 18s
	45m 38s

Provide feedback