Update Sector to core 8.9.13

There' s a new security advisory out for Drupal core: https://www.drupal.org/sa-core-2021-001

We're currently on 8.9.10 and we need to bump that up to 8.9.13 and tag a new minor release: 5.0.0 => 5.0.1

A proper contrib update pass for D8 is planned for later this month or next, alongside the launch of the 9.1.0 series.