minor #61371 chore: PHP CS Fixer - restore PHP / PHPUnit rulesets (keradus)

This PR was squashed before being merged into the 7.4 branch.

Discussion
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 chore: PHP CS Fixer - restore PHP / PHPUnit rulesets

| Q             | A
| ------------- | ---
| Branch?       | 7.4
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Issues        | Fix CS <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT

relates to symfony/symfony@5d4e211#r163638626 , showing:
- possible improvements to codebase that those ruleset can still offer (especially when targetting newest possible target version)
- and also preventing old way to still be in use, if someone forget to use new syntax/methods

with love by [PHP Coding Standards Fixer](https://cs.symfony.com/)

Commits
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92940de5e52  chore: PHP CS Fixer - restore PHP / PHPUnit rulesets

Author: nicolas-grekas

bin/simple-phpunit.php

@@ -165,7 +165,7 @@
 $prevCacheDir = getenv('COMPOSER_CACHE_DIR');
 if ($prevCacheDir) {
     if (false === $absoluteCacheDir = realpath($prevCacheDir)) {
-        @mkdir($prevCacheDir, 0777, true);
+        @mkdir($prevCacheDir, 0o777, true);
         $absoluteCacheDir = realpath($prevCacheDir);
     }
     if ($absoluteCacheDir) {
@@ -181,7 +181,7 @@
 if (!file_exists("$PHPUNIT_DIR/$PHPUNIT_VERSION_DIR/phpunit") || $configurationHash !== @file_get_contents("$PHPUNIT_DIR/.$PHPUNIT_VERSION_DIR.md5")) {
     // Build a standalone phpunit without symfony/yaml nor prophecy by default
 
-    @mkdir($PHPUNIT_DIR, 0777, true);
+    @mkdir($PHPUNIT_DIR, 0o777, true);
     chdir($PHPUNIT_DIR);
     if (file_exists("$PHPUNIT_VERSION_DIR")) {
         passthru(sprintf('\\' === \DIRECTORY_SEPARATOR ? 'rmdir /S /Q %s 2> NUL' : 'rm -rf %s', escapeshellarg("$PHPUNIT_VERSION_DIR.old")));