[BUGFIX] Avoid warnings about ObjectStorage with PHPStan 1.11.9

It looks like PHPStan 1.11.9 considers the offending line to be
different in version 1.11.9.

To be compatible with both PHPStan <= 1.11.9 and 1.11.9, we now
need two `@phpstan-ignore-next-line` entries.

Fixes #167

Author: oliverklee

stubs/ObjectStorage.stub

@@ -42,6 +42,7 @@ class ObjectStorage implements \Iterator, \ArrayAccess
      * @phpstan-ignore-next-line See https://forge.typo3.org/issues/98146
      * @return string|null
      */
+    // @phpstan-ignore-next-line See https://forge.typo3.org/issues/98146
     public function key();
 
     /**