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

Tests/Util/GitRepositoryTest.php

@@ -40,7 +40,7 @@ public function testItThrowsAnExceptionIfInitialisedWithNonGitDirectory()
     {
         $this->expectException(RuntimeException::class);
 
-        @mkdir($this->targetDir, 0777, true);
+        @mkdir($this->targetDir, 0o777, true);
 
         new GitRepository($this->targetDir);
     }