v2.9.0

• Feature: Support union types and address deprecation of ReflectionType::getClass() (PHP 8+).
  (#198 by @cdosoftei and @SimonFrings)

  $promise->otherwise(function (OverflowException|UnderflowException $e) {
      echo 'Error: ' . $e->getMessage() . PHP_EOL;
  });

• Feature: Support intersection types (PHP 8.1+).
  (#195 by @bzikarsky)

  $promise->otherwise(function (OverflowException&CacheException $e) {
      echo 'Error: ' . $e->getMessage() . PHP_EOL;
  });

• Improve test suite, use GitHub actions for continuous integration (CI),
  update to PHPUnit 9, and add full core team to the license.
  (#174, #183, #186, and #201 by @SimonFrings and #211 by @clue)