apply phpcs to tests

[kawanamiyuu]

    "scripts": {
        "check":["@lint", "@test"],
        "test": "phpdbg -qrr ./vendor/bin/phpunit --coverage-text",
        "lint": [
-           "phpcs --standard=PSR12 src",
+           "phpcs --standard=PSR12 src tests",
            "phpmd src text cleancode,codesize,controversial,design,naming,unusedcode",
            "phpstan analyze --no-progress --level=max src"
        ],
-       "fmt": "phpcbf --standard=PSR12 src"
+       "fmt": "phpcbf --standard=PSR12 src tests"
    },