Remove dependency on deprecated stable

Yes, please. The theme is not Drupal 10 compatible if it has a dependency on stable.

This theme cannot be used in Drupal 10 because it requires either Drupal 8 (any version that is higher or equal to 8.8) or Drupal 9 (any version).

What should be done is:

• Create a new branch for Drupal 9/10 and higher versions
• Change the base theme from Stable to Stable9
• Update all the project dependencies with versions that work on Drupal 10
• Change the core_version_requirement line to include Drupal 10

As a side note, it seems that the development of the AdaptiveTheme theme (the one that was forked to create this theme) started again. This theme should be considered unsupported.