Drupal\Tests\text_block\Kernel\TextBlockTest fails by calling undefined function

Problem/Motivation

Drupal\Tests\text_block\Kernel\TextBlockTest fails by calling undefined function:

Error: Call to undefined function Drupal\block\Entity\system_region_list()

/core/modules/block/src/Entity/Block.php:349
/core/lib/Drupal/Core/Entity/EntityStorageBase.php:494
/core/lib/Drupal/Core/Entity/EntityStorageBase.php:449
/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php:263
/core/lib/Drupal/Core/Entity/EntityBase.php:339
/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php:591
/modules/contrib/text_block/tests/src/Kernel/TextBlockTest.php:50
/vendor/phpunit/phpunit/src/Framework/TestResult.php:691

Steps to reproduce

Try to run the test with
phpunit /web/modules/contrib/text_block/tests/src/Kernel/TextBlockTest.php

Proposed resolution

Add the system module to the module list to be installed before running the test, because it provides the required function.

Remaining tasks

Create patch for this, commit and create new release.

User interface changes

None

API changes

None

Data model changes

None