StatementList use Iterator;

psalm in my own project complains about this issue, as `Iterator` is missing a use statement

Author: addshore

src/Statement/StatementList.php

@@ -6,6 +6,7 @@
 use Comparable;
 use Countable;
 use InvalidArgumentException;
+use Iterator;
 use IteratorAggregate;
 use Traversable;
 use Wikibase\DataModel\Entity\PropertyId;