Fix implicit nullable parameter on PHP 8.4 (#897)

Fix Implicitly marking parameter on PHP 8.4

This will get one extra test green.

There are plenty of other issues emitted by actual non-stub Drupal core code.

2) mglaman\PHPStanDrupal\Tests\StubTest::testValid
array (
  0 =>
  array (
    'message' => 'Deprecated in PHP 8.4: Parameter #2 $account (Drupal\\Core\\Session\\AccountInterface) is implicitly nullable via default value null.',
    'file' => '/Users/dpi/Code/phpstan-drupal/src/Drupal/../../stubs/Drupal/Core/Access/AccessibleInterface.stub',

Co-authored-by: Matt Glaman <[email protected]>

Author: dpi

stubs/Drupal/Core/Access/AccessibleInterface.stub

@@ -13,5 +13,5 @@ interface AccessibleInterface {
    *
    * @return ($return_as_object is true ? \Drupal\Core\Access\AccessResultInterface : bool)
    */
-    public function access(string $operation, AccountInterface $account = NULL, bool $return_as_object = FALSE);
+    public function access(string $operation, ?AccountInterface $account = NULL, bool $return_as_object = FALSE);
 }