Issue #3246673: Move PendingUpdatesValidator into Package Manager

package_manager/tests/src/Kernel/PendingUpdatesValidatorTest.php

@@ -11,6 +11,11 @@ use Drupal\package_manager\ValidationResult;
  */
 class PendingUpdatesValidatorTest extends PackageManagerKernelTestBase {
 
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['system'];
+
   /**
    * Tests that no error is raised if there are no pending updates.
    */