Restore paratest (#3335)

.github/workflows/tests.yaml

@@ -38,4 +38,4 @@ jobs:
 
             -   uses: "ramsey/composer-install@v1"
 
-            -   run: vendor/bin/phpunit ${{ matrix.path }} --colors
+            -   run: vendor/bin/paratest ${{ matrix.path }} --colors --verbose

composer.json

@@ -13,6 +13,7 @@
         "composer/semver": "^3.3.2",
         "composer/xdebug-handler": "^3.0.3",
         "doctrine/inflector": "^2.0.6",
+        "fidry/cpu-core-counter": "0.5.1 as 0.4.1",
         "nette/utils": "^3.2.9",
         "nikic/php-parser": "^4.15.3",
         "ondram/ci-detector": "^4.1",
@@ -27,7 +28,7 @@
         "rector/rector-php-parser": "dev-main",
         "rector/rector-phpunit": "dev-main",
         "rector/rector-symfony": "dev-main",
-        "sebastian/diff": "^5.0",
+        "sebastian/diff": "5.0 as 4.0.4",
         "symfony/config": "^6.2",
         "symfony/console": "^6.2.2",
         "symfony/contracts": "^3.2",
@@ -39,6 +40,7 @@
         "webmozart/assert": "^1.11"
     },
     "require-dev": {
+        "brianium/paratest": "^7.0",
         "cweagans/composer-patches": "^1.7.2",
         "icanhazstring/composer-unused": "^0.8.5",
         "myclabs/php-enum": "^1.8.4",