* Updated Python support and dependencies.
* Updated Python support in README.
* Removed PY36 from GHA workflow.
* Remove pre-commit workflow. Fixes#397
* Updated Black in pre-commit to 22.3.0.
* Update all pre-commit hooks.
* [pre-commit.ci] auto fixes from pre-commit.com hooks
* Lint with pre-commit
* Move existing tox qa hooks into pre-commit.
* Set up GitHub Action based on https://github.com/pre-commit/action/ (we could also use https://pre-commit.ci ).
* Add `pyupgrade` to drop old Python syntax.
* Add `flake8-bugbear` plugin to prevent flake8 errors.
* Drop custom GHA
