Remove grasmash/yaml-expander as it is not used

[alexpott]

Necessary for drush to work on Drupal 10.0.x

$ composer require drush/drush 11.x-dev

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - grasmash/yaml-expander[1.1.1, ..., 1.2.0] require symfony/yaml ^2.8.11|^3 -> found symfony/yaml[v2.8.11, ..., 2.8.x-dev, v3.0.0-BETA1, ..., 3.4.x-dev] but the package is fixed to v5.4.2 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
    - grasmash/yaml-expander[1.3.0, ..., 1.x-dev] require symfony/yaml ^2.8.11|^3|^4 -> found symfony/yaml[v2.8.11, ..., 2.8.x-dev, v3.0.0-BETA1, ..., 3.4.x-dev, v4.0.0-BETA1, ..., 4.4.x-dev] but the package is fixed to v5.4.2 (lock file version) by a partial update and that version does not match. Make sure you list it as an argument for the update command.
    - drush/drush 11.x-dev requires grasmash/yaml-expander ^1.1.1 -> satisfiable by grasmash/yaml-expander[1.1.1, ..., 1.x-dev].
    - Root composer.json requires drush/drush 11.x-dev -> satisfiable by drush/drush[11.x-dev].