Switch from Psalm to PHPStan level 6 #598

	name: Static analysis

	on:
	push:
	pull_request:

	jobs:
	phpcs:
	name: PHP-CodeSniffer
	runs-on: ubuntu-latest

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

	- name: Set up PHP
	uses: shivammathur/setup-php@v2
	with:
	php-version: '8.3'
	extensions: bcmath, gmp, intl, dom, mbstring

	- name: Download dependencies
	run: composer install --classmap-authoritative

	- name: PHP CS
	run: vendor/bin/phpcs

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