Pin pytest to <7 #461

Job	Run time
Lint (black)	39s
Check for news fragments in 'changelog.d/'	11s
Test Python 3.8, Django 3.2, Redis.py latest	4m 47s
Lint (flake8)	31s
Test Python 3.8, Django 4.0, Redis.py latest	4m 39s
Lint (isort)	34s
Test Python 3.8, Django 4.1, Redis.py latest	4m 49s
Lint (mypy)	46s
Test Python 3.8, Django 4.2, Redis.py latest	4m 42s
Test Python 3.9, Django 3.2, Redis.py latest	5m 2s
Test Python 3.9, Django 4.0, Redis.py latest	4m 43s
Test Python 3.9, Django 4.1, Redis.py latest	4m 44s
Test Python 3.9, Django 4.2, Redis.py latest	4m 43s
Test Python 3.10, Django 3.2, Redis.py latest	5m 8s
Test Python 3.10, Django 4.0, Redis.py latest	4m 55s
Test Python 3.10, Django 4.1, Redis.py latest	4m 53s
Test Python 3.10, Django 4.2, Redis.py latest	4m 33s
Test Python 3.6, Django 3.2, Redis.py latest	5m 13s
Test Python 3.7, Django 3.2, Redis.py latest	5m 0s
Test Python 3.11, Django 4.1, Redis.py latest	5m 2s
Test Python 3.11, Django 4.2, Redis.py latest	4m 38s
Test Python 3.11, Django 4.2, Redis.py master	4m 45s
Test Python 3.11, Django main, Redis.py latest	5m 0s
Test Python 3.11, Django main, Redis.py master	5m 13s
	1h 35m 10s

Provide feedback