Allow newer Drush for newer Drupal

[adam-vessey]

#8 fixed solidly to drush 10 to maintain compatibility with Drupal 8 and 9; however, we now have Drupal 10 in our testing matrix, for which drush 11 is required... so let it be used accordingly.

Should hopefully address some tests which blow up due to Drush 10 not supporting Drupal 10, such as:

• https://github.com/Islandora/islandora/runs/6678217486?check_suite_focus=true#step:9:433

     Problem 1
      - drush/drush[10.0.0-alpha1, ..., 10.3.5] require composer/semver ^1.4 -> found composer/semver[1.4.0, ..., 1.x-dev] but the package is fixed to 3.3.2 (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.
  Error: Your requirements could not be resolved to an installable set of packages.
  

• https://github.com/Islandora/islandora/runs/6728671150?check_suite_focus=true#step:9:430

     Problem 1
      - drush/drush[10.0.0-alpha1, ..., 10.3.5] require composer/semver ^1.4 -> found composer/semver[1.4.0, ..., 1.x-dev] but the package is fixed to 3.3.2 (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.
  Error: Your requirements could not be resolved to an installable set of packages.