* 🔧 Add pre-commit config
Similar to graphene and graphene-sqlalchemy
* ⬆ Bump black
* 👷 Lint on CI
* ⬆ Bump flake8-black
* 🔧 Keep excluding migrations
* ⬆ Bump flake8
* 🔧 Remove black and flake8 from tox config
* ⬆ Update pre-commit versions
* Upgrade syntax to python 3.7+
* Format with pre-commit
dedent docs/schema.py to allow formatting
* Fix tests on python 3.7
* Update Django's main branch name
* Add Python 3.9 to tox
* Update base gh action versions
* Add Django 3.2 to tests
* Remove redundant Django 1.11 references
* Update setup.py for new Django and Python versions
