Try removing require-dev

tests/src/Build/CoreUpdateTest.php

@@ -9,6 +9,12 @@ namespace Drupal\Tests\automatic_updates\Build;
  */
 class CoreUpdateTest extends UpdateTestBase {
 
+  protected function getInitialConfiguration(array $data): array {
+    $data = parent::getInitialConfiguration($data);
+    unset($data['require-dev']);
+    return $data;
+  }
+
   /**
    * {@inheritdoc}
    */