theme_get_setting() has been deprecated in Drupal 11.3

Problem/Motivation

theme_get_setting() is deprecated in Drupal 11.3. Instead, the new Drupal\Core\Extension\ThemeSettingsProvider service should be used.

This means that the following code needs to be changed.

  $form['seven_settings']['enable_block_contextual_links'] = [
    '#type' => 'checkbox',
    '#title' => t('Enable contextual links for blocks'),
    '#default_value' => theme_get_setting('enable_block_contextual_links'),
  ];

Proposed resolution

Change the code which calls theme_get_setting(). For code that works either before or after Drupal 11.3, see DeprecationHelper helps modules support multiple versions of core.