Add lint >= 8.0 directive to skip test on PHP 7.4

The test file uses `mixed` type hints which require PHP 8.0+.

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

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-11234.php

@@ -1,4 +1,4 @@
-<?php
+<?php // lint >= 8.0
 
 namespace Bug11234;