Issue #3239556 by andypost: Fix return type of...

Issue #3239556 by andypost: Fix return type of \Drupal\Tests\migrate\Kernel\TestFilterIterator::accept()

core/modules/migrate/tests/src/Kernel/TestFilterIterator.php

@@ -10,7 +10,7 @@ class TestFilterIterator extends \FilterIterator {
   /**
    * {@inheritdoc}
    */
-  public function accept() {
+  public function accept(): bool {
     return TRUE;
   }