Add back #[RequiresPhp('>= 8.0')] to testBug6934

The test data file uses DOMNode which has version-dependent property
types via #[LanguageLevelTypeAware] in phpstorm-stubs. On PHP < 8.0,
the analysis may produce different errors since DOMNode::$parentNode
lacks a native type declaration. The // lint >= 8.0 comment in the
test data file is only processed by TypeInferenceTestCase, not by
RuleTestCase::analyse(), so #[RequiresPhp] is needed to skip the
test on older PHP versions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -3945,6 +3945,7 @@ public function testBug7369(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.0')]
 	public function testBug6934(): void
 	{
 		$this->checkThisOnly = false;