Your requirements could not be resolved to an installable set of packages.
Problem 1
- drupal/memcache[2.0.0-alpha1, ..., 2.0.0] require drupal/core ~8.0 -> found drupal/core[8.0.0-beta6, ..., 8.9.x-dev] but it conflicts with your root composer.json require (11.x-dev).
- drupal/memcache 2.1.0 requires drupal/core ^8 || ^9 -> found drupal/core[8.0.0-beta6, ..., 8.9.x-dev, 9.0.0-alpha1, ..., 9.5.x-dev] but it conflicts with your root composer.json require (11.x-dev).
- drupal/memcache[2.2.0-rc1, ..., 2.2.0] require drupal/core ^8.8 || ^9 -> found drupal/core[8.8.0-alpha1, ..., 8.9.x-dev, 9.0.0-alpha1, ..., 9.5.x-dev] but it conflicts with your root composer.json require (11.x-dev).
- drupal/memcache 2.3.0 requires drupal/core ^8.9 || ^9 -> found drupal/core[8.9.0-beta1, ..., 8.9.x-dev, 9.0.0-alpha1, ..., 9.5.x-dev] but it conflicts with your root composer.json require (11.x-dev).
- drupal/memcache[2.4.0, ..., 2.x-dev] require drupal/core ^9.1 || ^10 -> found drupal/core[9.1.0-alpha1, ..., 9.5.x-dev, 10.0.0-alpha1, ..., 10.1.x-dev] but it conflicts with your root composer.json require (11.x-dev).
- acquia/memcache-settings[v1.0.0, ..., 1.x-dev] require drupal/memcache ^2.0 -> satisfiable by drupal/memcache[2.0.0-alpha1, ..., 2.x-dev].
- Root composer.json requires acquia/memcache-settings ^1 -> satisfiable by acquia/memcache-settings[v1.0.0, v1.1.0, v1.2.0, 1.x-dev].