minor #61373 chore: PHP CS Fixer - heredoc indentation as of PHP 7.3 (keradus)

This PR was merged into the 7.4 branch.

Discussion
----------

 chore: PHP CS Fixer - heredoc indentation as of PHP 7.3

| 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

inspired by symfony/symfony@06e22b0#r2265021821

[Possible since PHP 7.3](https://www.php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc)

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

Commits
-------

4a25a6a5785 chore: heredoc indentation as of PHP 7.3

Author: nicolas-grekas

Tests/Node/NodeTest.php

@@ -23,10 +23,10 @@ public function testToString()
         $node = new Node([new ConstantNode('foo')]);
 
         $this->assertEquals(<<<'EOF'
-Node(
-    ConstantNode(value: 'foo')
-)
-EOF
+            Node(
+                ConstantNode(value: 'foo')
+            )
+            EOF
             , (string) $node);
     }