Update `tox.ini` to test more versions of `django` / `djangorestframework` #6

	name: Review

	on: [push, pull_request]

	jobs:
	review:
	name: Run linters and tests
	runs-on: "ubuntu-20.04"
	strategy:
	matrix:
	python: ["3.6", "3.7", "3.8", "3.9", "3.10", "3.11"]

	steps:
	- name: Checkout the source code
	uses: actions/checkout@v2

	- name: Set the python version
	uses: actions/setup-python@v3
	with:
	python-version: ${{ matrix.python }}

	- name: Install dependencies
	uses: ./.github/actions/install
	with:
	python-version: ${{ matrix.python }}

	- name: Run tests

	# Python 3.6 tests have been removed since swagger-spec-validator no longer supports it.
	# A successful workflow run for Python 3.6 is required by the GitHub branch protection rules.
	if: ${{ matrix.python != 3.6 }}

	env:
	PYTHON_VERSION: ${{ matrix.python }}
	run: tox -e $(tox -l \| grep py${PYTHON_VERSION//.} \| paste -sd "," -)

	- name: Report coverage
	if: ${{ matrix.python == 3.9 }}
	run: \|
	pip install coverage
	coverage report

	- name: Check for incompatibilities with publishing to PyPi
	if: ${{ matrix.python == 3.8 }}
	run: \|
	pip install -r requirements/publish.txt
	python setup.py sdist
	twine check dist/*

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