Problem with sitemap_update_8101()

Problem/Motivation

When I upgrade the module from previous versions to the latest one, I'm getting this error:

 [notice] Update started: sitemap_update_8101
 [error]  Drupal\Core\Entity\EntityStorageBase::loadMultiple(): Argument #1 ($ids) must be of type ?array, string given, called in /app/source/web/modules/contrib/sitemap/sitemap.install on line 14
 [error]  Update failed: sitemap_update_8101
 [error]  Update aborted by: sitemap_update_8101
 [error]  Finished performing updates.

This happens because \Drupal\user\RoleStorage::loadMultiple(?array $ids = NULL): array (inherited from \Drupal\Core\Entity\EntityStorageBase::loadMultiple(?array $ids = NULL): array), but the update hook passes a string instead.

Steps to reproduce

Install and configure 'drupal/sitemap:^2.0@RC', then upgrade to the latest version 'drupal/sitemap:^2.0'. Running drush updb, you will get the error.

Proposed resolution

Fix the call to loadMultiple():

- loadMultiple('administer site configuration');
+ loadMultiple(['administer site configuration']);

Remaining tasks

1. Write a merge request - done by @programeta in #2
2. Review and feedback - done by @dhruv.mittal in #5
3. RTBC and feedback - done by @mparker17 in #6
4. Commit - done by @mparker17 in #11
5. Release - released in version 8.x-2.1

User interface changes

None.

API changes

None.

Data model changes

None.