Add missing use statement for get_class() in ObjectType

Fix coding standard violation: get_class() should be referenced via
a use statement, not as a fallback global name.

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

Author: phpstan-bot

src/Type/ObjectType.php

@@ -56,6 +56,7 @@
 use function array_map;
 use function array_values;
 use function count;
+use function get_class;
 use function implode;
 use function in_array;
 use function sprintf;