v2.8.0

• Mark FulfilledPromise, RejectedPromise and LazyPromise as deprecated for Promise v2 (and remove for Promise v3).
  (#143 and #165 by @clue)

  // deprecated
  $fulfilled = new React\Promise\FulfilledPromise($value);
  $rejected = new React\Promise\RejectedPromise($reason);
  
  // recommended alternatives
  $fulfilled = React\Promise\resolve($value);
  $rejected = React\Promise\reject($reason);

• Fix: Fix checking whether cancellable promise is an object and avoid possible warning.
  (#168 by @smscr and @jsor)

• Improve documentation and add docblocks to functions and interfaces.
  (#135 by @CharlotteDunois)

• Add .gitattributes to exclude dev files from exports.
  (#154 by @reedy)

• Improve test suite, run tests on PHP 7.4 and update PHPUnit test setup.
  (#163 by @clue)