Added a feature to optionally override existing environment variables set by the system #617

Run details

	name: "CI"

	on:
	pull_request:
	push:
	branches:
	- '1.x'
	- '2.x'

	env:
	SYMFONY_PHPUNIT_DIR: "$HOME/symfony-bridge/.phpunit"

	jobs:
	tests:
	name: "PHP ${{ matrix.php }} ${{ matrix.mode }}"

	runs-on: ubuntu-latest

	strategy:
	fail-fast: false
	matrix:
	include:
	- php: '8.0'
	composer: 2.2.x
	- php: '8.1'
	- php: '8.2'
	- php: '8.3'
	- php: '8.4'
	- php: '8.1'
	mode: low-deps

	steps:
	- name: "Checkout code"
	uses: actions/checkout@v4

	- name: "Install PHP"
	uses: shivammathur/setup-php@v2
	with:
	coverage: "none"
	php-version: ${{ matrix.php }}
	tools: composer:${{ matrix.composer }}

	- if: matrix.php == '8.0'
	name: "Lint PHP files"
	run: \|
	find src/ -name '*.php' \| xargs -n1 php -l
	find tests/ -name '*.php' \| xargs -n1 php -l

	- name: "Validate composer.json"
	run: "composer validate --strict --no-check-lock"

	- name: "Install dependencies"
	run: \|
	if [[ "${{ matrix.mode }}" = low-deps ]]; then
	composer u --prefer-lowest --prefer-stable --ansi
	else
	composer u --ansi
	fi

	- name: "Install PHPUnit"
	run: vendor/bin/simple-phpunit install

	- run: vendor/bin/simple-phpunit