Update dependency wp-phpunit/wp-phpunit to v6 #535

	name: Test plugin
	on: [push, pull_request]

	jobs:
	tag:
	name: PHP ${{ matrix.php }} / WP ${{ matrix.wp }} Test
	runs-on: ubuntu-latest
	services:
	mysql:
	image: mysql:5.7
	env:
	MYSQL_ALLOW_EMPTY_PASSWORD: true
	MYSQL_ROOT_PASSWORD: root
	MYSQL_DATABASE: wordpress_test
	ports:
	- 3306:3306
	options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=3
	strategy:
	matrix:
	include:
	- php: 8.0
	wp: latest
	- php: 7.4
	wp: latest
	steps:
	- name: Checkout
	uses: actions/checkout@master
	- name: PHP ${{ matrix.php }} / WP ${{ matrix.wp }} Test
	uses: shivammathur/setup-php@v2
	with:
	php-version: ${{ matrix.php }}
	extensions: mbstring, intl , mysqli
	ini-values: post_max_size=256M, short_open_tag=On #optional, setup php.ini configuration
	coverage: xdebug #optional, setup coverage driver

	- name: Check PHP Version
	run: php -v

	- name: Install phpunit global
	run: \|
	composer global require "phpunit/phpunit=7..\|8.."
	phpunit --version

	- name: Cache composer packages
	uses: actions/cache@v2
	with:
	path: vendor
	key: composer-${{ hashFiles('composer.lock') }}

	- name: Composer install
	run: \|
	composer install --optimize-autoloader --prefer-dist
	composer fund

	- name: Coding Style check
	run: composer lint

	- name: Install WP Tests
	run: bash bin/install-wp-tests.sh wordpress_test root root 127.0.0.1 ${{ matrix.wp }} true

	- name: phpunit tests
	run: \|
	phpunit
	WP_MULTISITE=1 phpunit

Provide feedback