chore: add ci tests for --prefer-lowest

.github/workflows/ci-3.x.yml

@@ -37,13 +37,20 @@ jobs:
  strategy:
  matrix:
  # All the versions, OS, and dependency levels we want to support
- php: [8.0, 8.1, 8.2]
- dependency: [stable] # TODO: lowest
  os: [ubuntu] # TODO: windows, macos
  # Our code has paths for with- and without- XDebug, and we want to test
  # both of them.
  # @see https://xdebug.org/docs/all_settings#mode
  xdebug3-mode: ["xdebug.mode=develop,coverage", "xdebug.mode=coverage"]
+ include:
+ - php: '8.0'
+ dependency: 'prefer-lowest'
+ - php: '8.0'
+ dependency: 'prefer-stable'
+ - php: '8.1'
+ dependency: 'prefer-stable'
+ - php: '8.2'
+ dependency: 'prefer-stable'
 
  name: PHP ${{ matrix.php }} on ${{ matrix.os }}, ${{ matrix.dependency }} dependencies preferred
  runs-on: ${{ matrix.os }}-latest